Place milk , butter and flour in a pan over a medium heat, and wisk. continuously until sauce thicken.
Remove from heat , stir in cream , parmesan cheese and season with salt and pepper.
Stir fry the ham , garlic and mushrooms until the mushrooms are cooked.
Add ham mixture to the sauce and reheat.
Place the cooked drained pasta in a large bowl .
Add the carbonarra sauce and mix well.
Serve hot , sprinkled with parmesan cheese.