Put flour, icing sugar, vanillin sugar, 1 pinch of salt, 1 egg, 1 tablespoon cold water and 125 g butter in flakes into a mixing bowl. Knead first with the dough hooks of the hand mixer, then briefly with your hands to a smooth short pastry. Wrap the dough in foil and chill for approx. 30 minutes
Grease a tart mould (26 cm Ø) with lift-off base and dust with flour. Roll out the dough on a lightly floured, large sheet of baking paper to form a circle (approx. 30 cm Ø) and line the tin with it. Press the dough to the edge so that it stands approx. 1/2 cm above the edge. Prick the base of the dough several times with a fork. Place the mould in a cool place for 15-20 minutes
Wash the strawberries, drain well, clean and cut in half. Bake the tart in a preheated oven, lower shelf (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 20 minutes
In the meantime, grate the chocolate coarsely, mix with 120 g nuts and baking powder. Separate 3 eggs. Beat the egg whites until stiff, adding 1 pinch of salt at the end. Mix 50 g soft butter and sugar until creamy. Stir in the egg yolks one by one. Add rum and chocolate-nut mixture and stir in. Fold in beaten egg white
Remove the pre-baked tart base from the oven. Sprinkle the base with approx. 2 tbsp. ground hazelnuts. Spread the strawberries on top and spread the hazelnut chocolate mixture on top. Bake at the same temperature on the bottom rack for another 25-30 minutes. Let the finished tart cool in the tin on a cake rack for about 20 minutes. Then remove from the tin and let it cool down. Dust with icing sugar if necessary
Waiting time approx. 1 hour