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Stacked brookies showing fudgy brownie bases and golden chocolate chip cookie layers

Brookies with Brownie and Cookie Layers

Fudgy cocoa brownies and chewy chocolate chip cookie dough bake together in a 9 x 13-inch pan, with clear cues for judging each layer and cutting 24 neat brookies.
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Prep Time 35 minutes
Cook Time 35 minutes
Cooling 2 hours
Total Time 3 hours 10 minutes
Servings: 24 bars
Course: Dessert
Cuisine: American
Calories: 310
Ingredients Equipment Method Notes

Ingredients
  

  • 170 g (3/4 cup) unsalted butter For the brownie layer, cut into pieces
  • 113 g (4 oz) semisweet or bittersweet chocolate For the brownie layer, finely chopped
  • 250 g (1 1/4 cups) granulated sugar For the brownie layer
  • 2 large eggs For the brownie layer, at room temperature
  • 2 tsp pure vanilla extract For the brownie layer
  • 65 g (3/4 cup) unsweetened cocoa powder Natural or Dutch-process, sifted
  • 95 g (3/4 cup) all-purpose flour For the brownie layer
  • 1/2 tsp fine sea salt For the brownie layer
  • 170 g (3/4 cup) unsalted butter For the cookie layer, softened to about 18 to 20°C
  • 150 g (3/4 cup packed) light brown sugar For the cookie layer
  • 75 g (6 tbsp) granulated sugar For the cookie layer
  • 1 large egg For the cookie layer, at room temperature
  • 1 large egg yolk For the cookie layer, at room temperature
  • 2 tsp pure vanilla extract For the cookie layer
  • 220 g (1 3/4 cups) all-purpose flour For the cookie layer
  • 8 g (1 tbsp) cornstarch For the cookie layer
  • 1/2 tsp baking soda For the cookie layer
  • 1/2 tsp fine sea salt For the cookie layer
  • 170 g (1 cup) semisweet chocolate chips For the cookie layer

Equipment

  • 9 x 13 inch light-colored metal baking pan
  • Parchment paper
  • Digital kitchen scale and measuring spoons
  • Two large mixing bowls
  • Medium heatproof bowl or saucepan
  • Electric hand mixer or sturdy whisk
  • Flexible silicone spatula
  • Fine-mesh sieve
  • Wire cooling rack
  • Long sharp knife

Method
 

  1. Position a rack in the center of the oven and preheat to 175°C or 350°F. Lightly grease a 9 x 13-inch light-colored metal pan, then line the bottom and long sides with parchment, leaving enough overhang to lift the slab later. Grease the exposed short sides. A metal pan conducts heat more predictably than glass, which helps the central brownie set before the perimeter becomes hard.
  2. In a large bowl, beat the softened cookie-layer butter, brown sugar, and granulated sugar with a hand mixer on medium speed for 2 minutes, until creamy and slightly aerated but not fluffy. Beat in the egg, yolk, and vanilla until smooth. Whisk the flour, cornstarch, baking soda, and salt separately, then mix them into the butter mixture on low just until no dry flour remains. Fold in the chocolate chips and refrigerate the dough for 15 minutes.
  3. Place the brownie-layer butter and chopped chocolate in a medium heatproof bowl. Set it over a saucepan containing about 2.5 cm or 1 inch of barely simmering water, keeping the bowl above the water. Stir until approximately three-quarters melted, then remove from the heat and continue stirring until completely smooth. Let the mixture stand for 5 minutes. Cooling it briefly prevents the eggs from heating too quickly and helps preserve a stable, glossy batter.
  4. Whisk the granulated sugar into the warm chocolate mixture. Add the eggs one at a time, whisking vigorously for about 30 seconds after each, then whisk in the vanilla until the batter looks smooth and slightly thickened. Sift the cocoa powder, flour, and salt directly over the bowl. Fold with a flexible spatula, scraping the bottom and sides, just until the final flour streak disappears. The batter should fall from the spatula in thick, glossy ribbons.
  5. Scrape the brownie batter into the prepared pan and spread it into an even layer, taking care to reach the corners. Remove the cookie dough from the refrigerator and flatten portions about the size of a heaped tablespoon into rough 1 cm-thick pieces. Arrange them closely over the batter, leaving narrow channels of brownie visible between the pieces. Do not press the dough into the batter. The exposed spaces allow heat and steam to move through the thicker top layer.
  6. Bake for 32 to 36 minutes, rotating the pan from front to back after about 22 minutes if your oven browns unevenly. The cookie layer should have pale golden centers, deeper golden edges, and a dry, set surface. Insert a toothpick into an exposed brownie area near the center, avoiding chocolate chips. It should emerge with several moist crumbs but no shiny liquid batter. If the cookie top darkens early, loosely cover the pan with foil for the remaining time.
  7. Set the pan on a wire rack and cool the brookies completely in the pan for at least 2 hours. The center continues setting as the melted fats cool, so cutting sooner can produce compressed, messy layers even when fully baked. Run a thin knife along the unlined edges, lift the slab out using the parchment, and place it on a cutting board. Use a long sharp knife to cut 24 bars, wiping the blade clean between cuts for distinct layers.

Notes

  • Use a light-colored metal pan. Dark pans can brown the cookie edges before the central brownie is set, while glass heats and cools more slowly and may extend the baking schedule.
  • Keep the cookie butter softened but cool. If it looks glossy or leaves an oily film in the bowl, chill it briefly before mixing so the topping does not spread into a thin, hard sheet.
  • Flatten the cookie dough into pieces of similar thickness. Large mounds remain doughy after the exposed brownie is done, while very thin pieces become crisp before the center sets.
  • For especially tidy squares, cool the slab fully, refrigerate it for 20 to 30 minutes, and then slice with a warm, dry knife. Let the cut bars return to room temperature before serving.