For the blueberry tart, mix the whole eggs with the sugar and vanilla sugar until very foamy, stir in the rum, then gently fold in the flour with the baking powder using a pastry card.
Line a springform pan with baking paper and pour in the batter. Bake for about 10 minutes, turn out onto the cake plate, remove the paper and place a cake ring around the sponge.
Spread with jam if desired. Cook the pudding as indicated on the package, spread on the pastry and chill. Meanwhile, cook the cake jelly according to package directions, refrigerate slightly.
Spread the blueberries on the pudding and spread the tart jelly evenly on top with a tablespoon.
Before serving, decorate with whipped cream.