Are they French? Italian? Austrian? No matter where they come from, they taste great!
Cut the sausage lengthwise into thin long slices and then diagonally into fine strips. Grate the cheese.
Use a frying pan with a little oil to brown the sausage until it is slightly crispy. Strain it on a paper towel. Use a sharp knife (preferably a serrated one) to slice the croissants in half, but not completely, so that the edges stick.
Stuff the croissants with a mixture of cheese and sausage, then bake at 180 °C (356 °F) for about 8–10 minutes.