In a bowl, mix the ricotta, parmesan and nutmeg well.
Take a tray and cover with a layer of the semolina. With your hands, form the ricotta into small balls about 1.5 inches wide, roll in a plate of semolina and place on the tray. Sprinkle over more semolina when you have finished; you want to make sure each ball has been covered well. Place in the fridge overnight.
To make the sauce, chop the onion and place in a saute pan with the olive oil. Cook on a medium heat for 2 minutes, then add the anchovy fillets and olives. Crush the olives with your wooden spoon, and continue cooking until the anchovy fillets have almost disintegrated.
Tip in the tomatoes, simmer for 5 minutes, then season and stir in the chopped basil.
To cook the gnudi, bring a large pan of water to the boil. Gently place the gnudi in the water (it is best to cook them in small batches) and boil for 3 minutes. Remove with a slotted spoon.
Layer gnudi in each person’s bowl and pour over the sauce. Bellissimo!