Preheat oven to 380 degrees F. Thaw one sheet of puff pastry until room temperature. Roll the pastry dough into circle and transfer to a parchment lined baking sheet. Prick with a fork.
Bake for 12-15 minutes.
Peel the apples and cut them in half through the stem. Remove the stems and slice the apples cross wide in very thin slices. Add lemon juice.
Arrange the apples slices in an overlapping spiral pattern.
In a medium bowl beat the eggs with sugar. Add calvados, sour cream and almond powder, mix well.
Pour the mixture over the apples.
Bake for another 15 minutes.
Sprinkle with sliced almonds and keep baking for 30 more minutes until golden.
Remove from the oven and cool in the pan. Transfer to serving plate and sprinkle with powdered sugar.