1. Wash and peel the potatoes.
Cook the potatoes in water or steam them. In a bowl, mash the cooked potatoes.
2. Add the egg yolks and mix well.
3. Add the butter, nutmeg, salt, and pepper.
4. Preheat the oven to 220°C (425°F). Place a tablespoon of mashed potatoes in each muffin cup.
5. Press a piece of cheese into the center of each muffin.
6. Use the back of a spoon to smooth the surface of the muffins to cover the cheese.
7. Sprinkle with grated cheese.
8. Bake for 15 minutes.
9. Remove from the muffin cups and serve hot!