Brown Butter Plum Upside-Down Cake with Caramelized Plums

Jammy purple plums, buttery caramel, and a fragrant hazelnut-like crumb give this brown butter plum upside-down cake a lovely contrast of juicy fruit and tender cake. The plum wedges soften without disappearing, while their tart edges balance the brown sugar topping. Underneath, almond flour keeps the crumb plush without making it heavy or damp.

I brown the butter until the milk solids are deep golden, then cool it until barely warm so it emulsifies with the eggs and dairy instead of creating a greasy batter. The finished cake should spring back at the center and show moist crumbs, never wet batter, on a tester. After baking, a precise 15-minute pan rest is the sweet spot for turning it out cleanly.

What Makes this Brown Butter Cake Deliciously Ridiculous

• Browning the butter concentrates its dairy solids into toasted, nutty flavors that remain distinct beneath the assertive plum topping.
• A combination of all-purpose flour and finely ground almond flour produces a tender but sufficiently sturdy crumb that supports the juicy fruit layer.
• Placing plum skins against the lined pan creates a colorful finished surface while the exposed flesh absorbs the butter and brown sugar.
• Room-temperature eggs, sour cream, and milk help the fluid brown butter form an even emulsion, preventing greasy pockets in the baked crumb.
• A 15-minute rest after baking allows steam to subside and the crumb to firm while the fruit caramel is still warm enough to release.

Ingredient Notes for Brown Butter Plum Upside-Down Cake with Caramelized Plums

• Plums: Use ripe but firm red, black, or purple plums. Very soft fruit releases excessive juice and can make the top watery. Weigh the plums after removing the pits, then cut uniformly so they soften at the same rate.
• Unsalted butter: Butter for the batter is browned with its milk solids, which provide the cake’s nutty flavor. Keep every browned particle because those dark golden flecks contain much of the flavor. The separate melted butter belongs in the fruit topping.
• Light brown sugar: Its molasses content helps form a soft caramel beneath the plums. Pack it evenly over the butter without leaving thick mounds that could turn syrupy.
• All-purpose flour: This supplies enough gluten-forming protein to support the fruit. Measure by weight and stop mixing as soon as the last dry streaks disappear to avoid a tough crumb.
• Almond flour: Finely ground blanched almond flour adds fat and tenderness while absorbing some fruit moisture. Coarse almond meal will produce a rougher, more fragile crumb.
• Sour cream: Full-fat sour cream contributes moisture, acidity, and body. Plain full-fat Greek yogurt may be used at the same weight, although its slightly higher protein can make the crumb marginally firmer.
• Eggs and milk: Bring both to room temperature before mixing. Cold liquid can cause the melted brown butter to seize into small fat particles instead of dispersing evenly through the batter.
• Baking powder and salt: Baking powder lifts the relatively rich batter, while fine salt sharpens the caramel, plum, and toasted butter flavors. Check that the baking powder is fresh before starting.

My Tips for the Best Results

• Choose plums that yield slightly near the stem but still hold their shape when sliced. Rock-hard plums remain sharply tart, while overripe ones can collapse and release enough liquid to soften the cake’s surface.
• Use a light-colored saucepan for browning the butter. A dark interior hides the changing milk solids, making it much easier to move from toasted brown to bitter black.
• Arrange the plums tightly because they shrink as they bake. Leaving large spaces exposes patches of brown sugar that can harden instead of becoming a fruit-enriched caramel.
• Do not pour hot brown butter directly into cold eggs or sour cream. Cooling the butter and tempering the dairy to room temperature protects the emulsion and gives the cake a uniform crumb.
• Set a timer for the 15-minute inversion window. Turning the cake out immediately risks tearing its delicate hot crumb, while leaving it in the pan too long allows the caramelized fruit to adhere.

Ingredients for Brown Butter Plum Upside-Down Cake

• 28 g unsalted butter (2 tablespoons, melted, for the fruit topping)
• 90 g light brown sugar (about 7 tablespoons, packed, for the fruit topping)
• 500 g ripe but firm plums (pitted weight, cut into wedges about 8 mm thick)
• 170 g unsalted butter (3/4 cup, cut into pieces, for browning and using in the cake batter)
• 200 g all-purpose flour (about 1 2/3 cups, spooned and leveled if not weighed)
• 40 g finely ground blanched almond flour (about 1/3 cup)
• 6 g baking powder (1 1/2 teaspoons)
• 3 g fine sea salt (1/2 teaspoon)
• 150 g granulated sugar (3/4 cup)
• 2 large eggs (about 100 g without shells, at room temperature)
• 10 g pure vanilla extract (2 teaspoons)
• 120 g full-fat sour cream (1/2 cup, at room temperature)
• 60 g whole milk (1/4 cup, at room temperature)

How to Make Brown Butter Plum Upside-Down Cake

• STEP 1). Prepare the oven and cake pan Heat a conventional oven to 350°F (175°C) with a rack in the lower-middle position. Trace the base of a solid 9 x 2-inch metal cake pan onto parchment and cut out the circle. Lightly grease the pan sides, fit the parchment snugly over the bottom, and set the pan on a dry work surface. Avoid a springform pan because the warm butter and sugar topping can leak through its seam.
• STEP 2). Brown and cool the butter Place the 170 g butter in a small light-colored saucepan and melt it over medium heat. Continue cooking for 5 to 7 minutes, swirling frequently as the butter foams and crackles. Remove it from the heat when the foam subsides, the milk solids are deep golden brown, and the aroma is distinctly nutty. Immediately scrape the butter and every browned particle into a heatproof bowl. Cool for about 15 minutes, until fluid but only barely warm.
• STEP 3). Build the caramelized plum layer Pour the 28 g melted butter over the parchment-lined pan and tilt the pan to coat the base. Sprinkle the brown sugar evenly over the butter, breaking up firm lumps with your fingertips. Arrange the plum wedges skin-side down in tight, slightly overlapping concentric circles, filling the center with smaller pieces. Keep the fruit in one even layer rather than stacking it, which helps the cake bake level and limits pools of uncooked juice.
• STEP 4). Combine the dry ingredients Set a fine-mesh sieve over a medium bowl and add the all-purpose flour, almond flour, baking powder, and salt. Sift the mixture, then whisk for about 20 seconds to distribute the almond flour and leavener evenly. Break apart any almond flour clumps that remain. This even distribution matters because concentrated pockets of almond flour can turn pasty beside the fruit, while uneven baking powder can leave tunnels in the crumb.
• STEP 5). Emulsify the brown butter batter In a large bowl, whisk the cooled brown butter and granulated sugar for 45 seconds; the mixture will look glossy and slightly grainy rather than creamed. Whisk in the eggs one at a time, mixing thoroughly after each, then add the vanilla. Whisk in the sour cream until smooth, followed by the milk. The mixture should be cohesive and satiny. If small butter flecks appear, let the bowl stand in a warm spot for 2 minutes and whisk again.
• STEP 6). Finish the batter and bake Add the dry mixture to the wet ingredients in two additions, folding with a flexible spatula just until no flour streaks remain. The batter should be thick, smooth, and able to fall slowly from the spatula. Spoon it gently over the plums, then spread it to the edge without disturbing the pattern. Bake for 47 to 52 minutes, until the center springs back, the top is golden, and a tester inserted in the center returns with moist crumbs but no wet batter.
• STEP 7). Rest, invert, and cool Transfer the pan to a wire rack and leave the cake undisturbed for exactly 15 minutes. Run a thin offset spatula around the side without cutting toward the fruit. Center a flat serving plate over the pan, protect your hands with dry oven mitts, and invert both in one confident motion. Wait 30 seconds before lifting the pan, then peel away the parchment. Reposition any attached plum gently and cool for at least 1 hour before slicing with a sharp knife.

Storage and Freezing

• Room temperature: Keep the completely cooled cake covered for up to 1 day in a cool room. Do not cover it while warm because trapped condensation makes the plum surface watery.
• Refrigeration: Store covered in the refrigerator for up to 4 days. Place a piece of parchment against a cut edge to slow drying without pressing plastic wrap onto the fruit.
• Freezing: Freeze individual cooled slices on a parchment-lined tray until firm, then wrap and place in an airtight container for up to 2 months. The plums will be softer after freezing, but the crumb remains suitable for serving.
• Thawing: Unwrap frozen slices and thaw them on a covered plate in the refrigerator overnight so condensation does not collect inside the wrapping.
• Serving: Bring refrigerated slices to room temperature for 30 minutes, or warm individual pieces in a 300°F (150°C) oven for 8 to 10 minutes. Avoid overheating, which can make the fruit topping slide from the crumb.

Frequently Asked Questions

More Ridiculously Delicious Cakes

• Pineapple Upside-Down Cake with Golden Caramelized Pineapple
• Pear Almond Upside-Down Cake with Toasted Almond Crumb
• Cranberry Orange Upside-Down Cake with Bright Citrus and Caramel
• Chocolate Peanut Butter Sheet Cake with Soft, Tender Crumb
• Cranberry Orange Coffee Cake with Soft, Tender Crumb

Brown Butter Plum Upside-Down Cake with Caramelized Plums

A 9-inch upside-down cake with a glossy layer of caramelized plums over a tender almond crumb flavored with nutty brown butter. Resting the baked cake for 15 minutes before inversion lets the topping settle while the caramel remains fluid enough to release cleanly.

Print Recipe Pin Recipe

Prep Time 30 minutes mins

Cook Time 55 minutes mins

Cooling 1 hour hr 15 minutes mins

Total Time 2 hours hrs 40 minutes mins

Servings: 10 slices

Course: Dessert

Cuisine: American

Calories: 397

Ingredients Equipment Method Notes

Ingredients

  

• 28 g unsalted butter 2 tablespoons, melted, for the fruit topping
• 90 g light brown sugar about 7 tablespoons, packed, for the fruit topping
• 500 g ripe but firm plums pitted weight, cut into wedges about 8 mm thick
• 170 g unsalted butter 3/4 cup, cut into pieces, for browning and using in the cake batter
• 200 g all-purpose flour about 1 2/3 cups, spooned and leveled if not weighed
• 40 g finely ground blanched almond flour about 1/3 cup
• 6 g baking powder 1 1/2 teaspoons
• 3 g fine sea salt 1/2 teaspoon
• 150 g granulated sugar 3/4 cup
• 2 large eggs about 100 g without shells, at room temperature
• 10 g pure vanilla extract 2 teaspoons
• 120 g full-fat sour cream 1/2 cup, at room temperature
• 60 g whole milk 1/4 cup, at room temperature

Equipment

• 9 x 2-inch solid round metal cake pan
• Parchment paper
• Digital kitchen scale
• Small light-colored saucepan
• Heatproof bowl
• Large and medium mixing bowls
• Fine-mesh sieve
• Balloon whisk
• Flexible silicone spatula
• Offset spatula
• Wire cooling rack
• Flat serving plate at least 10 inches wide

Method

 

1. Heat a conventional oven to 350°F (175°C) with a rack in the lower-middle position. Trace the base of a solid 9 x 2-inch metal cake pan onto parchment and cut out the circle. Lightly grease the pan sides, fit the parchment snugly over the bottom, and set the pan on a dry work surface. Avoid a springform pan because the warm butter and sugar topping can leak through its seam.
2. Place the 170 g butter in a small light-colored saucepan and melt it over medium heat. Continue cooking for 5 to 7 minutes, swirling frequently as the butter foams and crackles. Remove it from the heat when the foam subsides, the milk solids are deep golden brown, and the aroma is distinctly nutty. Immediately scrape the butter and every browned particle into a heatproof bowl. Cool for about 15 minutes, until fluid but only barely warm.
3. Pour the 28 g melted butter over the parchment-lined pan and tilt the pan to coat the base. Sprinkle the brown sugar evenly over the butter, breaking up firm lumps with your fingertips. Arrange the plum wedges skin-side down in tight, slightly overlapping concentric circles, filling the center with smaller pieces. Keep the fruit in one even layer rather than stacking it, which helps the cake bake level and limits pools of uncooked juice.
4. Set a fine-mesh sieve over a medium bowl and add the all-purpose flour, almond flour, baking powder, and salt. Sift the mixture, then whisk for about 20 seconds to distribute the almond flour and leavener evenly. Break apart any almond flour clumps that remain. This even distribution matters because concentrated pockets of almond flour can turn pasty beside the fruit, while uneven baking powder can leave tunnels in the crumb.
5. In a large bowl, whisk the cooled brown butter and granulated sugar for 45 seconds; the mixture will look glossy and slightly grainy rather than creamed. Whisk in the eggs one at a time, mixing thoroughly after each, then add the vanilla. Whisk in the sour cream until smooth, followed by the milk. The mixture should be cohesive and satiny. If small butter flecks appear, let the bowl stand in a warm spot for 2 minutes and whisk again.
6. Add the dry mixture to the wet ingredients in two additions, folding with a flexible spatula just until no flour streaks remain. The batter should be thick, smooth, and able to fall slowly from the spatula. Spoon it gently over the plums, then spread it to the edge without disturbing the pattern. Bake for 47 to 52 minutes, until the center springs back, the top is golden, and a tester inserted in the center returns with moist crumbs but no wet batter.
7. Transfer the pan to a wire rack and leave the cake undisturbed for exactly 15 minutes. Run a thin offset spatula around the side without cutting toward the fruit. Center a flat serving plate over the pan, protect your hands with dry oven mitts, and invert both in one confident motion. Wait 30 seconds before lifting the pan, then peel away the parchment. Reposition any attached plum gently and cool for at least 1 hour before slicing with a sharp knife.

Notes

• Choose plums that yield slightly near the stem but still hold their shape when sliced. Rock-hard plums remain sharply tart, while overripe ones can collapse and release enough liquid to soften the cake’s surface.
• Use a light-colored saucepan for browning the butter. A dark interior hides the changing milk solids, making it much easier to move from toasted brown to bitter black.
• Arrange the plums tightly because they shrink as they bake. Leaving large spaces exposes patches of brown sugar that can harden instead of becoming a fruit-enriched caramel.
• Do not pour hot brown butter directly into cold eggs or sour cream. Cooling the butter and tempering the dairy to room temperature protects the emulsion and gives the cake a uniform crumb.
• Set a timer for the 15-minute inversion window. Turning the cake out immediately risks tearing its delicate hot crumb, while leaving it in the pan too long allows the caramelized fruit to adhere.