Peel and quarter the apples and remove the core. Cut quarters into thin slices and sprinkle with lemon juice. Boil 440 ml apple juice and 200 g sugar. Stir pudding powder and remaining apple juice until smooth.
Stir into the boiling juice, bring to the boil and simmer for about 1 minute. Remove from the heat, stir in the apples and let them cool down for about 1 hour.
Put flour, butter in flakes, 175 g sugar, baking powder and egg in a bowl. Knead first with the dough hooks of the hand mixer, then with your hands to a shortcrust pastry. Press the dough into a greased springform pan (26 cm Ø) sprinkled with flour as a base and rim.
Spread the apple mixture on the dough. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 45 minutes. Remove and let cool on a cake rack.
Mix sour cream and 2 teaspoons of sugar. Whip the cream with the whisk of the hand mixer until stiff, fold into the sour cream. Carefully remove the cake from the tin and place on a cake plate. Spread the sour cream loosely on the cake.
Dust with cinnamon.