Yield: 10 - 12 servings
Return berries and drained syrup to same saucepan. Boil syrup until thickened and reduced to 1 2/3 cups, about 5 minutes. Transfer boysenberry sauce to small bowl. Cover and refrigerate.
Position rack in center of oven and preheat to 350°F. Coat 9-inch-diameter springform pan with 2 3/4-inch-high sides with margarine. Crumble cake onto large baking sheet. Bake until crumbs are dry and just beginning to color, about 15 minutes. Cool. Maintain oven temperature. Finely grind crumbled cake in processor.
Sprinkle 1/3 of cake crumbs in bottom of prepared pan. Sprinkle 2/3 cup almonds over. Sprinkle 1/3 of macaroons over. Top with half of apple slices. Mix apricot preserves and brandy in small bowl. Spread half of apricot mixture over apples. Repeat layering with half of remaining crumbs, almonds, macaroons and margarine. Press top firmly to compact cake.
Place cake on baking sheet. Bake until top is golden and cake just begins to shrink from sides of pan, covering loosely with foil for last 15 minutes if browning too quickly, about 45 minutes. Transfer cake to rack. Press top firmly to compact cake. Cool cake in pan on rack. Cover and chill overnight. (Can be prepared 2 days ahead.)
Run small sharp knife around sides of pan to loosen cake. Release pan sides. Whip cream and 3 tablespoons sugar to firm peaks. Spread cream over top and sides of cake. Press additional almond slices onto sides of cake. Refrigerate at least 1 hour and up to 4 hours.
Cut cake into wedges. Spoon reserved boysenberry sauce over.
10 to 12 servings