Drain the ricotta of any liquid and put it in a bowl with 2/3 of the grated Parmigiano, the egg, the egg yolk and the flour, after passing it through a sieve. Grate a little nutmeg and some lemon zest and a pinch of salt into the mixture.
Mix everything carefully with a fork. You can also use your hands but you don’t want to knead this dough, just make sure all the ingredients are well incorporated. Cover the bowl with cling film and leave it to rest for at least 2 hours in the fridge.
Place some baking paper on a tray and sprinkle with semolina flour (or normal flour) You can use wet hands to make the balls. I used an ice-cream/melon scope to get the same quantity of gnudi mixture for each ball. Place the gnudi balls on the tray and roll a little to cover each ball slightly in flour.
Put a pot of water onto boil and, in the meantime, melt the butter in a skillet or frying pan. It needs to brown but not burn. Cook the gnudi in the boiling water for 2-4 minutes, as soon as they come to the surface remove with a slotted spoon.
The cooking time will depend on the size of your gnudi. Then either add them to the pan with the melted the butter or plate them and pour the butter over them. Serve with a sprinkling of Parmigiano and truffle shavings.
If you don’t have black truffles you can serve these ricotta gnudi with just the browned butter and grated cheese. Otherwise, see the article for other recipe ideas.