Preheat the oven to 350 degrees and coat an 8x8 baking dish with cooking spray.
Make the topping by mixing all ingredients together until well combined. Set aside.
In a saucepan melt butter over moderately low heat. Remove pan from heat and stir in sugar and vanilla.
Add eggs, 1 at a time, beating well with a wooden spoon after each addition.
Sift the flour, cocoa powder, baking powder, and salt into a separate bowl add to the sugar mixture until just combined well.
Spread batter evenly in pan.
Bake brownies in the middle of the oven for 20 minutes.
Remove from oven and add topping to the top then continue to bake for an additional 15-20 minutes or until a tester comes out of the center with crumbs adhering to it.
Cool brownies completely in a pan on a rack before cutting. Enjoy.