Line a springform pan with baking paper, place puff pastry on top, pulling up one edge. Spread the apples on the puff pastry, put in the oven for 10 minutes.
While the apples are prebaking, stir the softened butter with icing sugar until smooth, mix with sour cream and flour to form a thick glaze. After 10 minutes of baking, spread the topping on the apples and finish baking the cake in approx. 20 minutes. The casting should turn a light brown. Let cool and serve.