Cream the fat with the whisk of the hand mixer. Stir in eggs and 150 g sugar. Mix flour, 100 g cornstarch, baking powder, salt and lemon peel. Add flour and milk to the eggs and mix. Grease a star-shaped baking tin (30 cm Ø) and sprinkle with breadcrumbs. Pour the dough into the form and bake in the preheated oven (electric: 175 °C/ gas:stage 2) for 50-60 minutes. Let the dough rest in the pan for about 10 minutes, then turn out onto a cake rack and let it cool down. Cut the star horizontally once.
Cut a thick slice from 1 grapefruit. Peel the rest of the grapefruit so that the white skin is completely removed. Remove the fillets between the parting skins. Squeeze the grapefruit. Cut fillets in half, except for 7 pieces for decoration. Whip 250 g cream, 4 tablespoons sugar and vanillin sugar until stiff. Remove approx. 5 tablespoons of 1/4 l grapefruit juice and mix with remaining starch. Bring the grapefruit juice to the boil and stir in the starch. Let it cool down a little bit and stir in the cream by the spoonful. Carefully fold in the halved fillets. Turn the upper half of the star and spread the mixture evenly. Place the lower half of the star on top, press down lightly and smooth down the excess filling. Refrigerate star for about 1 hour. Whip the remaining cream and sugar until very stiff. Fill 3 tablespoons of cream into a piping bag with star spout.
Bring the grapefruit juice to the boil and stir in the starch. Let it cool down a little bit and stir in the cream by the spoonful. Carefully fold in the halved fillets. Turn the upper half of the star and spread the mixture evenly. Place the lower half of the star on top, press down lightly and smooth down the excess filling. Refrigerate star for about 1 hour. Whip the remaining cream and sugar until very stiff. Fill 3 tablespoons of cream into a piping bag with star spout. Spread the cake all around with the remaining cream. Sprinkle the sides of the star with hazelnut leaves. Decorate the middle of the star with the remaining grapefruit fillets. Spray a cream dab on each star tip. Divide the grapefruit slice into six. Spread the whole hazelnuts on the cream dab. Results in about 16 pieces
Spread the cake all around with the remaining cream. Sprinkle the sides of the star with hazelnut leaves. Decorate the middle of the star with the remaining grapefruit fillets. Spray a cream dab on each star tip. Divide the grapefruit slice into six. Spread the whole hazelnuts on the cream dab. Results in about 16 pieces
Preparation time: approx. 1 1/4 hours (without waiting time)