Preheat oven to 325 degrees. Lightly spray a 9x9" pan with non-stick baking spray. Set aside.
In a separate bowl, whisk together the cocoa powder, flour, baking powder and salt. Gradually add the dry ingredients to the wet ingredients, using a whisk to mix together. Batter will be very thick.
Pour batter into prepared pan, and spread evenly. Bake for 33-35 minutes at 325 degrees. Remove brownies from oven and let cool to room temperature.
While the brownies bake, make the coconut pecan frosting. In a medium sauce pan, whisk together the evaporated milk, brown sugar and egg yolks. Then, add the butter. Add saucepan to stovetop and heat over medium-low heat to melt the butter. Whisk or stir often to incorporate the butter as it melts. Once butter is completely melted, bring to a low simmer and cook for 8-10 minutes stirring often.
Once cooked, remove from heat and stir in the coconut and pecans. Let frosting cool completely.
Once brownies and frosting have cooled to room temperature, spread the frosting over the top of the brownies. Top with additional chopped pecans and mini chocolate chips, if desired.