1. Heat oven to 350 degrees F. Line bottoms of two 9-inch-round cake pans with waxed paper.
2. Sift flour, cocoa, baking powder, baking soda, cinnamon, cloves and salt into bowl. Whisk prune puree, milk, egg whites, whole egg, vanilla and sugar in large bowl until smooth. Whisk flour mixture into prune mixture just until mixed. Divide equally between prepared cake pans.
3. Bake in 350 degrees F oven 20 to 25 minutes until tops are firm and wooden pick inserted in centers comes out clean. Transfer pans to racks to cool for 5 minutes. Invert cakes onto racks. Peel off paper.Prepare Icing:
4. Melt chocolate in top of double boiler over hot water. Whisk in sour cream; whisk in liqueur. Refrigerate 15 minutes or until the icing starts to become firm. Beat with whisk or beater until light and fluffy, 1 to 2 minutes.To assemble the cake:
5. Place one cake layer on bottom of inverted cake pan or on cardboard circle. Spread preserves over top of layer. Place second cake on top, smooth side up. Spread icing over the top and side of cake with a spatula. Wet the spatula, and smooth top.