Paisley Brownies

Preparation : Preheat the oven to 300 degrees F. Place the raspberries in the bowl of a food processor fitted with a metal blade. Pulse until liquefied, about 1 min. Strain the raspberries through a fine strainer into a 5 quart bowl, using a rubber spatula to press down on the seeds to extract as much puree as possible ( about 3/4 cup puree). Discard the seeds. Set the puree aside until needed. In a sifter combine the flour, baking powder, and salt. Sift onto a large piece of wax paper and set aside till needed. Heat 1 inch of water in the bottom half oa double boiler over med. heat. Place the white chocolate and 3 ounces of butter in the top half. Use a rubber spatula to stir the chocolate and butter until completely melted and smooth, about 5 min. Transfer the melted white chocolate and butter to an empty 5 qt bowl and set aside till needed. Again heat 1 inch of water in double boiler bottom ( as above) place the semisweet chocolate and the remaining 8 ozs of butter in the top half of the double boiler. Use a rubber spatula to stir the chocolate and butter until completely melted and smooth, about 7 min. Transfer the melted semisweet chocolate and butter to an empty 5 qt bowl and set aside until needed. Place the eggs, sugar and vanilla extract in the bowl of an electric mixer fitted with a ballon whip. Whisk on high for 2 min. until soft. Use a rubber spatula to scrape down the sides of the bowl, then whisk on high for 4 min until slightly thickented and lemon colored. operate the mixer on low whle gradually adding the sifted dry ingredients until incoporated, about 30 seconds. Remove the bowl from the mixer and add the sour cream. Use a rubber spatula to mix the ingredients until thoroughly combined. Portion 2 cups of batter into the bowl containing the pureerd raspberries and stir until smooth. Portion 1 cup of the batter into the bowl containing the melted white chocolate mixture and stir until smooth. Portion the remaining 2 cups of batter int o the bowl containing the melted semisweet chocolate mixture and stir until smooth. Pour the dark chocolate batter into 9x13x2 inch nonstick baking pan and spread evenly over the bottom. PJour the white chocolate batter onto the top of the dark chocolate batter in swirls. Pour the raspberry batter over the other two batters in the same manner. Use the blade of a paring knife to swirl the batter together in a fanciful pattern.. Bake on center rack of the preheated oven until a toothpick inserted in the center comes out clean. about 1 hour 10 min. Remove the brownies from the oven and allow to cool in the pan at room temperature for 1 hour. Use a serrated knife with rounded tip to cut the brownies into 24 2 inch squares. For a clean cut, heat the blade of the knife under hot running water and w ipe the blade dry before making each cut. Refrigerate the brownies for 2 -3 hours before serving.