You will be amazed by this brilliant trick! Worth a try
Ingredients:
Flour 300 gr
Butter 100 gr
Baking powder 1/2 tsp
Sour cream or yogurt 100 grams
Egg yolk 1 piece
Filling:
Apple 2 pieces
sugar 2 tablespoons
Butter 1 tablespoon
Chopped walnuts 50 g
Bake at 180°C for 30 minutes