This recipe was designed to be balanced which is why it uses 1/2 cup of milk and 1/2 cup of cream. If you want to make it super creamy, go ahead and use a full cup of cream. If you are looking to cut some of the fat and richness from the dish, you can use a full cup of milk. If you do this, let the sauce cook an extra 5-10 minutes to cook off some of the extra liquid.