For the base, knead flour, 75 g sugar, salt, egg, 1 tablespoon cold water and butter in flakes first with the dough hooks of the hand mixer then with your hands to a smooth dough. Spread it in a greased rectangular springform pan (24 x 36 cm) and press it to a base. Chill for about 30 minutes.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 12 minutes. Take out and let cool down.
For the cream, mix mascarpone, sour cream and 50 g sugar with the whisk of the hand mixer for about 2 minutes until creamy. Spread the cream on the cooled down base and smooth it down. Put it in a cold place. Soak gelatine in cold water. Peel the mango and cut the flesh off the stone.
Finely puree the mango, 50 g sugar and orange juice. Squeeze the gelatine, dissolve warm, stir in 2 tbsp. fruit puree and quickly stir the mixed gelatine mixture into the rest of the puree. Spread the fruit puree over the cream. Chill the cake for at least 4 hours.