Raspberry White Chocolate Angel Food

1 cup cake flour
1 1/2 cups powdered sugar
12 large egg whites, room temperature
1 1/2 teaspoons cream of tartar
1 cup sugar
1 tablespoon fresh lemon juice
2 teaspoons vanilla
3/4 cup fresh raspberries
5 ounces white chocolate, chopped

Position a rack in the center of the oven and preheat to 325�F. Have ready a 10-inch tube pan (preferably with removable bottom). Sift the cake flour and confectioners' sugar together onto a piece of waxed paper three times; set aside. In a large mixing bowl, whip the egg whites with an electric mixer at medium speed until frothy. Add the cream of tartar and beat at high speed, adding the sugar one tablespoon at a time, until the whites are glossy and stiff, but not dry. Add the lemon juice and vanilla and mix until just blended. Transfer the whites into a very large mixing bowl.

In several batches, re-sift the flour mixture over the whites; Using a large rubber spatula, gently fold in until just blended. Fold in the raspberries and white chocolate. Scrape the batter into the tube pan and bake 50 to 55 minutes, until the cake begins to pull away from the side of the pan. Remove the pan from the oven and invert over the neck of a bottle to keep it from collapsing. Cool the inverted cake completely. Turn the cake right-side-up and run a knife between the cake and the side of the pan to loosen it. Remove the side of the pan (it will still be attached to the base). Loosen the cake from the pan and invert the cake onto a plate.

TIPS: Make sure the egg whites are at room temperature. Cold eggs do not incorporate air as quickly and will not whip to their optimum capacity. Sifting the flour a minimum of 4 times allows the flour to incorporate into the egg mixture easily so that the egg whites do not deflate. The addition of an acid (e.g. cream of tartar, lemon juice) produces a whiter cake and stabilizes the egg white. Due to the tender and light structure of angel food cakes, it is imperative that all ingredients are measured precisely. Because of its low protein content and fine particles, cake flour is preferred over all-purpose flour and produces a more delicate, tender cake. (But all-purpose flour can be used). Add extracts (vanilla) at the last moment of whipping the whites. Adding them too soon will interfere with the volume of the whites.