Melt the butter in the pan, sweat the semolina in it, being careful not to burn anything on the bottom. Then deglaze with 1 liter of cold water, do not use warm water, otherwise there will be lumps.
Bring the soup to the boil. Then season with salt, pepper and nutmeg and then season with vegetable stock. Whisk the egg with a little milk and stir into the still hot soup, this will make delicious egg flakes.