Onions peel and chop finely. Peel garlic and chop finely. Clean the mushrooms, wash if necessary, and slice thinly. Put the noodles in plenty of boiling salted water and cook for about 10 minutes.
In the meantime, heat oil in a pan and fry onions until translucent. Add garlic, marjoram and mushrooms, fry briefly. Deglaze with broth and milk. Bring to the boil, stir in processed cheese, season with salt and pepper and bring to the boil again.
Stir in the sauce thickener and bring to the boil. Meanwhile quarter the tomatoes, remove seeds and cut into fine cubes. Pour pasta into a sieve, quench briefly and drain. Arrange noodles and sauce on plates, sprinkled with tomatoes and pepper.
Serve garnished with marjoram and mushroom slices as desired.