Preheat the oven to 350 degrees. Lightly grease a piece of parchment paper with butter and use it to line a 9-by-13-inch baking dish, leaving an overhang around the sides.

In a large bowl, whisk to combine the cocoa, flour, cinnamon, cayenne pepper, salt, and baking powder. Set aside.

Melt the 2 sticks of butter in a nonstick saucepan over medium-low heat (be sure not to boil). Remove from heat and let cool slightly.

Add the sugar and mix well with a large spoon.

Whisk each egg in a bowl and add to the saucepan one at a time, mixing well after each addition.

Add the vanilla and stir until combined.

Add the cocoa powder and flour mixture and mix until smooth.

Add 1/2 cup chocolate chips to the mixture and stir to combine.

Spread the batter in the prepared pan and sprinkle the other 1/2 cup chocolate chips to the top. Bake until a toothpick inserted in the middle comes out fudgy, about 20 to 25 minutes. Remove from oven and let the brownies cool in the pan. Use the parchment paper to lift out the brownies before slicing.