Preheat your oven to 350°F (175°C) and prepare a 9x13-inch baking dish.

In a medium saucepan, melt the unsalted butter over medium heat, swirling until golden and nutty—about 4–5 minutes.

In a large mixing bowl, combine the granulated sugar and light brown sugar, then pour in the cooled brown butter and mix until smooth.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract until combined.

In another bowl, whisk together flour, baking powder, baking soda, salt, and cocoa powder.

Gradually add the dry ingredients to the wet mixture, folding gently until just combined.

Fold in the chocolate chips and optional nuts, ensuring even distribution.

Pour the batter into the prepared baking dish, smoothing the top with a spatula.

Bake for 25–30 minutes, checking doneness with a toothpick until a few moist crumbs cling to it.

Let the brookies cool in the pan for at least 15 minutes, then cut into squares and serve warm.