Preheat the oven (electric cooker: 180 °C). Pour milk and 500 ml water into a large pot, salt lightly and bring to the boil. While stirring constantly with a whisk, sprinkle in the durum wheat semolina and cook for about 2 minutes until the mixture is semi-solid.
Remove from the heat and allow to cool slightly.
Stir the egg yolks into the warm semolina and season with 1 pinch of freshly grated nutmeg and salt and pepper. Pour the mixture onto an oiled marble or metal base and spread to a thickness of 1 cm.
Cool and let it set. Use a cookie cutter or glass to punch out circles of 4-5 cm in diameter. (You can bake the leftovers in the oven with tomatoes and mozzarella and serve as a snack. In Italy nothing is thrown away!).
Butter a casserole dish and place the semolina cookies in it, slightly overlapping. Spread the remaining butter in flakes over it. Season everything with salt and pepper. Sprinkle with the Parmesan and 1 more pinch of nutmeg and bake in the oven for 10 minutes.
Serve the gnocchi immediately.