Triple Chocolate Brownies

Instructions

1. Preheat the oven to 350℉. Lightly grease a 13x9 inch pan.
2. Place the unsweetened chocolate, semi-sweet chocolate and butter in medium microwavable bowl. Microwave on high for 2 minutes, or until butter is melted; stir until chocolate is completely melted. (If you don't wish to microwave, melt the chocolate in a bowl over a simmering pan of water). Cool until warm (no longer hot to touch).
3. Combine the flour, salt and baking powder in a small bowl. Set aside.
4. Beat the sugar, eggs and vanilla in a large bowl with an electric mixer at medium speed until slightly thickened. Beat in the chocolate mixture until well combined. Add the flour mixture; beat at low speed until blended. Add the sour cream; beat at low speed until combined. Stir in the chocolate chips.
5. Spread the mixture evenly into the prepared pan. Bake for 20 to 25 minutes, or until a toothpick inserted in the center comes out almost clean. Cool the brownies completely in the pan on a wire rack before cutting into 24 squares.
6. Place the powdered sugar in fine-mesh strainer and sprinkle over brownies.