Place the puff pastry slices next to each other and let them thaw at room temperature for about 10 minutes. Cut Cabanossi into slices. Whisk egg yolk with milk, place 5 slices on top of each other. Roll out squarely (approx. 26 x 26 cm) on a worktop dusted with flour. Cut out different large stars (2-13 cm Ø). Brush with egg yolk.
Put some of the smaller stars on top of the larger ones. Place on 3 baking trays lined with baking paper. Sprinkle with poppy seeds, sesame seeds and cheese, cover with cabanossi. Bake the trays one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 10 minutes. Serve lukewarm or cold