Beat the ricotta and Parmesan together in a bowl. Gently season with the nutmeg (too much and the gnudi take on a slightly medicinal flavour) and a good crack of pepper. Taste the mixture before adding salt.
Scatter a layer of semolina on a tray and fill a separate bowl with semolina, to a depth of about 5cm. Using two spoons, create little spheres from the ricotta and Parmesan mixture