**For the Brownie Layer:**
– 1/2 cup (1 stick) unsalted butter, melted
– 1 cup granulated sugar
– 2 large eggs
– 1/3 cup unsweetened cocoa powder
– 1/2 cup all-purpose flour
– 1/4 teaspoon salt
– 1/2 teaspoon vanilla extract

**For the Cookie Layer:**
– 1/2 cup (1 stick) unsalted butter, softened
– 1/2 cup brown sugar, packed
– 1/4 cup granulated sugar
– 1 large egg
– 1 teaspoon vanilla extract
– 1 1/4 cups all-purpose flour
– 1/2 teaspoon baking soda
– 1/4 teaspoon salt
– 1 cup chocolate chips