Fry the gyros together with the onions. Then add the peppers and sauté with them. In the meantime, cook the spaetzle or ribbon noodles al dente.
Mix the tzatziki, sour cream and cream (or milk) with chili powder, salt and tzatziki spice to taste.
Layer the gyros mixture and the spaetzle in a baking dish, pour the tzatziki mixture over it and finally sprinkle the cheese over it. Bake at 200 degrees for 10-15 minutes and then enjoy.