Finely grind almonds in processor. Sift flour and baking powder into small bowl. Set aside.
Using a stand mixer, cream butter with sugar until blended. Crumble the almond paste and beat in a few pieces at a time. Beat until mixture resembles smooth paste. Add eggs, 1 at a time, beating well after each addition. Add vanilla and beat until batter increases slightly in volume, about 5 minutes. Mix in almonds, then dry ingredients.
Divide batter between prepared pans. Bake until tester inserted in center of cakes comes out clean, about 55 minutes for 8-inch cake and 65 minutes for 12-inch cake. Cool cakes in pans on racks 10 minutes. Run small sharp knife around cake pan sides to loosen. Turn cakes out onto racks and cool completely.
Melt chocolate in top of double boiler over barely simmering water, stirring until smooth. Cool chocolate until just slightly warm.
Using stand mixer, beat butter until light. Gradually add cream cheese, beating until just combined. Beat in both extracts, add sugar and beat just until smooth. Add melted chocolate and beat until just combined. Stir in sour cream. Chill frosting until spreadable.
Place bottom 8-inch cake layer on 7-inch cardboard round. Spread with¼ cup berry filling, leaving ½ inch border uncovered. Carefully spread ¾ cup frosting over entire layer. Top with ¼ cup berry filling, leaving ½-inch border uncovered. Carefully spread ¾ cups frosting over entire layer. Top with top 8-inch cake layer. Chill cakes to set frosting (at least 2 hours) Spread a very light layer of frosting over the entire cake. The cake should not be completely covered. Chill again to set frosting (1 hour, or more). Spread 2 cups frosting over top and sides of cake. Chill both cakes for at least 3 hours.
Cut one 3-foot, 4-inch-long piece of ribbon and wrap around base of 12-inch cake. Press gently onto sides to adhere. Cut one 2-foot, 3-inch-long piece of ribbon and wrap around base of 8-inch cake. Press gently onto sides to adhere. Spoon remaining frosting into pastry bag fitted with small round tip. Pipe dots of frosting on top edge of both cakes. Refrigerate until frosting sets, about 1 hour. Arrange flowers atop cake. Serve cake cold or at room temperature.