Preheat the oven to 350°F (180°C).
In a mixing bowl, combine flour, cocoa powder, granulated sugar, and brown sugar.
Add melted butter to the dry ingredients and stir until combined.
Press the dough into a lightly greased baking dish and bake for 15 minutes.
In a clean bowl, mix together peanut butter and milk until smooth.
Spread the peanut butter mixture over the baked crust.
Melt the chocolate chips in the microwave or over a double boiler.
Pour the melted chocolate over the peanut butter layer and spread evenly.
Top with chopped peanuts if desired, and let it cool completely before slicing.