Bring the milk to boil in a pot and melt the butter into it. Season with a teaspoon of salt and grated nutmeg.
Add the semolina flour and mix quickly to avoid clumping. Cook for a further minute until the semolina becomes a compact mixture.
Remove from heat, mix in the yolk and 40g of the grated cheese.
Smear some oil on a deep tray and once the semolina mixture has cooled enough to handle, use a spatula and make a 1cm thickness 'cake' in the tray. Use a glass or a cookie cutter to cut out disks of gnocchi.
Place the gnocchi in a baking tray, placing them so that they overlapping each other a little. Sprinkle over the remaining cheese, bake in an oven at 200C for 20 min, until a crunchy crust has formed.