Pastry Base: Preheat oven to 180 degrees C. Use a 26cm springform tin.
Place the flour, baking powder, butter, 2 tbsp sugar, the egg and water in a bowl then knead to make a firm dough. Shape into a ball and cover with plastic wrap; chill for 30 minutes. Roll out the pastry to line the base and side of the tin. Bake for 15–20 minutes. Remove pastry base from tin; cool. Place a cake ring around it.
Chocolate Layer: Melt the chocolate in a bowl set over simmering water then spread over the pastry base.
Mango Cream: Peel mangoes. Slice flesh away from stone and cut into small cubes. Mix with the lemon juice. Set 12 cubes aside then puree the remaining flesh with the egg yolks and sugar. Heat 3 tbsp apple juice and dissolve gelatine in it. Stir into the mango cream with remaining apple juice. Chill. Whip cream until stiff then fold into the setting mango cream and pour over the pastry base. Cover the torte in cling wrap and chill overnight.
To Serve: Just before serving, whip the cream with a few drops of vanilla until stiff. Pipe onto cake. Decorate with 12 reserved mango cubes and the coarsely grated chocolate.