Cook the ribbon noodles according to the instructions on the packet. Peel and chop the onions.
Let the clarified butter melt in the pan, as soon as it is hot, add the onions. Fry it lightly brown and deglaze the whole thing with the tomatoes. Let it boil briefly and season with the spices.
Then add the sour cream and mozzarella. Melt the mozzarella while stirring and then add half of the fried onions.
Put the tagliatelle in a baking dish and spread the sauce over it (as it is very tough). Spread the rest of the fried onions on the sauce and sprinkle with Gouda cheese.
Bake at 200 ° C (fan oven) for approx. 15 minutes and then remove from the oven. The casserole is very easy to cut and does not disintegrate when serving.