Drain the plums and collect the juice. Stir starch and 2 tablespoons of juice until smooth. Boil up the rest of the juice, vanilla sugar, lemon peel and cinnamon stick in a pot. Stir in the mixed starch and let it swell at low heat for about 5 minutes. Add plums and schnapps, let compote cool down while stirring.
Remove lemon peel and cinnamon stick. Roast almond slivers in a pan without fat until golden brown. Whip cream until very stiff. Crumble the sponge finger roughly and mix with the almonds. Spread compote, cream and sponge cake crumbs in layers on four dessert glasses