Preheat the oven to 200°C (approximately 400°F). Place the thinly rolled pastry on a greased baking sheet (or place cut rectangles of dough in greased ramekins and bake all molds simultaneously in the oven; the baking time is reduced by half). Distribute onion rings, tomatoes, penne, feta cheese and rosemary on pastry, season with salt and pepper and bake in the hot oven for about 10 minutes.
Meanwhile mix cream with egg, then season with salt, pepper and nutmeg. Open the oven, pull out the sheet and spread the icing on the hot cake. Close the oven immediately and bake for 20 minutes until golden yellow. Allow to cool, cut into small squares and serve on small plates.