Preheat oven to 350°F. Line the bottom of a 9-inch round cake pan with parchment paper, and coat paper and sides of pan with butter. Set aside. Combine sugar, almond flour, baking powder and salt in a medium bowl. Stir to mix well and set aside.
Place egg whites in a large bowl and beat at high speed with an electric mixer until soft peaks form. Transfering to a bowl and set aside. Place butter in the same large mixing bowl and beat at medium-high speed with an electric mixer until fluffy. Beat in the almond paste, a few pieces at a time, beating well after each addition, until mixture is smooth.
for sauce Combine all ingredients in a food processor or blender; puree. Press mixture fine wire mesh sieve, discarding solids. Cover and chill. Makes 1 cup
Reduce speed to medium and gradually beat in the sugar mixture. Add the egg yolks and beat until a smooth batter forms. Beat in vanilla extract Gently fold in the egg whites in three additions, stirring until no white streaks remain. Spoon batter to prepared pan, smoothing the top. Bake 25 to 30 minutes or until top of cake is lightly browned.
Cool cake in pan for 5 minutes. Run a knife around the edge of the cake, remove cake from pan, discarding parchment paper, and cool completely on a wire rack Serve cake with Raspberry Sauce and fresh berries, sliced plums, or cherries. The cake can be covered in an airtight container and stored at room temperature up to 2 days.