Marbled Chocolate Brownies

Ingredients:
Brownies
1 bar (4 oz) bittersweet baking chocolate
1/2 cup (1 Stick) butter
2 tablespoons cocoa powder
1 1/4 cup sugar
1/4 teaspoon salt
3 eggs
1 teaspoon vanilla extract
1 cup all-purpose flour
1/2 teaspoon baking powder

Topping
1 cup semisweet chocolate chips
1 cup white chocolate baking chips

Step-by-step Instructions:

1.  Preheat oven to 350 degree. Line a 9-inch square baking pan with aluminum foil, making sure some of the foil hangs over the sides. Spray the foil with nonstick cooking spray.
2. Chop the bittersweet chocolate into small pieces. Place the chocolate, butter and cocoa powder in a microwave-safe bowl. Microwave on High until the chocolate and butter are melted. Stir to combine and set aside.
3. Place the sugar and salt in a medium bowl. Add the chocolate mixture, stirring to combine. Add the eggs, one at a time, stirring after each addition. Stir in the vanilla. Sift in the flour and baking powder; mix well.
4. Spread the batter in the prepared baking pan. Bake brownies for 30 minutes. Remove the pan from oven.
5. Sprinkle the chocolate chips over the brownies. Return brownies to over for 1 minute. Remove from oven; allow the pan to sit for 1 minute. Lift brownies out of the pan (using the foil for handles). Spread the chocolate chips over the brownies for a marbled effect. Let cool completely before cutting into bars.