Sift the flour and add the soft butter. Rub between your fingers the butter with the flour so as to obtain crumbs. Add yogurt and knead dough. Put it in the refrigerator for 30 minutes (or 10 minutes in the freezer). Clear apple from the seeds and stems and cut them into crescents, pour them with lemon juice. Once the dough has stayed right time knead it in seconds and roll out crust about 1 cm thick. Put it into the pan with a diameter of 20 cm. Arrange apples on top. Beat eggs with 3 tbsp sugar 3 tbsp flour and cinnamon. Pour mixture over apples. Bake in preheated oven at 180 C for about 30-something minutes or until apples browned, being careful not to burn the cake bottom. Consumes almost cold.