1Preheat oven to 350°F (175°C). Line an 8x8 inch pan with parchment paper.
2Prepare the cookie layer: Mix flour, baking soda, and salt. Set aside. Combine melted butter, brown and granulated sugar, egg, and vanilla. Whisk until smooth and fluffy for about 2-3 minutes. Add dry ingredients and chocolate chips. Mix until just combined.
3Prepare the brownie layer: Melt butter in a saucepan over medium-low heat. Stir every 10 seconds until foamy (6-8 minutes). Continue until milk solids turn golden brown and smell nutty. Transfer to a heatproof bowl. Add cocoa powder, oil, vanilla, and chopped chocolate; mix until smooth. In a separate bowl whisk 3 eggs and light brown sugar for 5-6 minutes until dissolved. Add powdered sugar; mix 1-2 minutes until combined. Add cooled browned butter mixture; mix until smooth. Add flour and chocolate chips; mix until well combined.
4Layer the cookie and brownie batters in the prepared pan.
5Bake for 50-55 minutes or until the edges are golden and center is a little jiggly. They will set once they are completely cooled.
6Let cool completely before cutting into brookies.
Ingredients
0.5 cups unsalted butter, melted and cooled
0.5 cups light brown sugar
0.33 cups granulated sugar
1 large egg, room temperature
1 tbsp vanilla extract
1.25 cups all-purpose flour, spooned and leveled
0.5 tsp baking soda
0.5 tsp flaky sea salt
1.5 cups semi-sweet chocolate chips
1 cup unsalted butter
0.5 cup Dutch-processed cocoa powder
1 tsp vanilla
0.5 cup light brown sugar, spooned and leveled
1.75 cups powdered sugar
0.75 cups semi-sweet chocolate chips
0.33 cups semi-sweet chocolate, chopped
3 eggs, room temperature
0.5 cup all-purpose flour
1 pinch salt
3 tbsp olive oil
Equipment
8*8 inch baking panparchment paperwhiskspatulasaucepan