Melt the margarine in a small pot. Stir in flour and sweat briefly. First add milk, bring to the boil while stirring, then stir in mascarpone. Prepare pasta in boiling salted water according to package instructions.
Add leaf spinach and diced ham to the sauce, bring to the boil and season with salt, pepper and nutmeg. If the sauce is a bit too thick, dilute with some broth. Drain the pasta, add to the sauce and serve.