Heat oven to 350 degrees. Line an 8 inch square baking pan with foil, letting foil extend above pan on 2 sides. Coat with nonstick spray.
Whisk flour, cocoa and baking powder in a medium bowl until thoroughly blended.
Melt butter and the 1 cup chocolate chips in a medium saucepan over low heat, stirring as needed. Remove form heat; whisk in sugar, then eggs and vanilla until blended. Scrape into flour mixture; stir until smooth. Stir in the 1/2 cup chips. Spread in prepared pan.
Bake 25 to 30 minutes or until a wooden pick inserted in center comes out with moist crumbs attached. Cool in pan on a wire rack.
Lift foil by ends onto cutting board. Cut into 16 squares.
Brownie Sundaes: Prepare Basic Brownies through step 5. Cut into 9 squares. Chocolate Sauce: Bring 1/3 cup water to a boil in a small saucepan or microwave-safe bowl. Remove from heat; add 1 cup semisweet chocolate chips and 1 teaspoon vanilla extract; stir until chocolate melts and sauce is smooth. Top each brownie with a scoop of ice cream, then warm chocolate sauce.
Brownie Pizza: Coat a 12 inch pizza pan with nonstick spray. Prepare Basic Brownies batter; spread in prepared pan. Sprinkle the 1/2 cup chocolate chips around edge. Bake 15 to 20 minutes until a wooden pick inserted in center comes out clean. Sprinkle 1 cup white chocolate chips in middle, let stand 5 minutes until soft, then spread to edge of semisweet chips. Immediately sprinkle with crispy M & M's and gummy fruits (about 1/4 cup each). Let cool. Cut into 12 wedges.
Brownie Drop Cookies: Coat foil-lined baking sheets with nonstick spray. Prepare Basic Brownies batter using only 1/2 stick butter or margarine. Stir in 1 cup each white chocolate chips and chopped walnuts. Let stand 5 to 10 minutes, then drop 1/4 cupfuls 2 inches apart on prepared baking sheets. Bake immediately for 12 minues or until cookies are puffed and shiny. Cool on foil 1 to 2 minutes, then remove to a wire rack to cool completely.
Brownie Coffeecake: Streusel Topping: Put 1/2 cup each flour, light brown sugar and chopped pecans and 1/2 stick softened butter in a bowl. Work with a fork until coarse crumbs form; set aside. Coat a 9 inch springform pan with nonstick spray. Prepare Basic Brownies batter increasing flour to 1 1/4 cups, adding 1/2 teaspoon baking soda to the flour mixture and stirring in 3/4 cup reduced-fat sour cream after the eggs and vanilla. Spread in prepared pan; sprinkle with streusel. Bake 50 to 55 minutes or until a wooden pick inserted in center of cake comes out clean.
Brownie Cupcakes with Cream Cheese Frosting: Line 12 regular muffin cups with paper or foil liners. Prepare Basic Brownies batter, adding a 3.8 oz box instant chocolate pudding to the ingredients in Step 2 and 2 extra large eggs in Step 3. Spoon into lined cups. Bake 30 to 33 minutes or until a wooden pick inserted in cemters comes out with moist crumbs attached. Cool in pan on wire rack; remove from pan. Frosting: Mix 2 ounces softened cream cheese and 1/2 stick softened butter or margarine in a medium bowl. Add 1 1/4 cups confectioners' sugar and 1/2 teaspoon vanilla extract; stir with a rubber spatula until smooth and well blended. Spread on cooled cupcakes.