Cut the ham into cubes. Wash, clean and halve the mushrooms. Wash, clean and halve or quarter the tomatoes. Heat 400 ml water and cream, stir in Gratin-Fix and bring to the boil while stirring.
Let simmer for 1 minute. Put the pasta, ham and vegetables in a flat casserole dish. Pour sauce over it, sprinkle with cheese and bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for about 30 minutes.
Serve garnished with parsley as desired.