Preheat oven to 350 degrees. Line a 9 inch square baking pan with enough foil to overhang two sides by 2 inches; coat with cooking spray. Combine flour, cocoa, salt and baking powder; reserve.
In microwave safe bowl, microwave chocolate chips and butter on high in 20 second intervals, stirring, until melted. Whisk in sugar, eggs and vanilla until blended. Stir in flour mixture until smooth.
Spread in pan. Bake 30-35 minutes or until pick inserted into center comes out clean. Cool on rack 15 minutes. Use foil to lift from pan. Cool completely before cutting.
Triple Peanut Brownies: Quarter 16 mini Snickers bars; stir into batter with 1 cup peanut butter M & M's. Bake 35-40 minutes. Stir 2 tablespoons creamy peanut butter into 1 can (16oz) vanilla frosting until smooth. Spread over cooled brownies. Sprinkle with additional M & M's and Snickers pieces.
German Chocolate Brownies: Stir 1 cup pecan pieces and 1/2 cup sweetened, flaked coconut into batter. Bake 35-40 minutes. Spread cooled brownies with 1 can (15 oz) coconut-pecan frosting. Sprinkle with 1/4 cup pecan pieces and 2 tablespoons sweetened, flaked coconut. Drizzle with 1/3 cup semisweet chocolate chips (melted).
Strawberry & White Chocolate Brownies: Stir 1/2 cup low suagr strawberry preserves, then 3/4 cup white chocolate chips into batter. Bake 40-45 minutes. Spread cooled brownies with 1 can (12 oz) whipped strawberry frosting. If desired, garnish with strawberries.
Grasshopper Brownies: Quarter 10 Double Stuf Oreo Mint cookies; stir into batter. Bake 35-40 minutes. Cut into bars; top with 1 can (16 oz) vanilla frosting and garnish with addditional cookie pieces.
Espresso Brownies: Add 3 tablespoons instant espresso coffee powder and 1/2 teaspoon grated lemon zest to butter mixture. Stir 3/4 cup mini chocolate chips into batter. Bake 40-45 minutes. Spread cooled brownies with 1 can (16 oz) milk chocolate frosting. If desired, garnish with chocolate curls and lemon zest twists.