Preheat oven to 350 degrees F. Prepare 8-inch square baking pan with non-stick spray. Set aside. Combine melted butter and cocoa powder. Set aside to cool. In large bowl beat eggs until frothy. Add Stevia Extract In the Raw and Sugar In The Raw. Combine flours, baking powder and salt – add to egg mixture and stir. Add in cocoa mixture, vegetable oil, buttermilk and vanilla. Stir until blended. Stir in mini chips. Pour batter into baking pan and bake at 350 degrees F about 20 minutes or until toothpick comes out clean. Remove from oven and cool on rack. Cut into 16 squares and serve.