Step 1Cook the macaroni in plenty of salted water until al dente, about 8 minutes. Drain and cool.
Step 2Mix together the prosciutto, cream, milk, Parmesan and nutmeg. Add the macaroni and season to taste with salt and pepper.
Step 3Spoon into a 11- by 7 1/2 -inch baking dish. Sprinkle grated Swiss cheese over the top.
Step 4Bake at 400 degrees until the cheese is lightly browned, about 20 to 25 minutes. For a crustier top, place the dish under a broiler for a few minutes.