Preheat the oven to 350°F (180°C).
Separate out 1/3 of the dough for the crust. Roll it out onto a floured service and cut out small round cookies. (I used a heart-shaped cookie cutter because I was serving the cake to lovers. You too are free to be creative.)
Butter a springform pan, 11 inch (28 cm) in diameter.
Roll ½ of the remaining dough out onto the bottom of the pan.
Press the remaining ½ of the dough along the inside walls of the pan.
Spread the poppy seed filling onto the crust.
Top with the apple filling.
Lay the cut-out cookies onto the top of the cake.
Combine the ½ egg yolk with 1 Tbsp of milk. Brush onto the cookies.
Bake for 40 minutes.
Eat your heart out.