Combine the cheeses and remove 1 1/2 cups of the cheese mixture for the topping.
Follow the al dente package directions for your pasta. When cooked, your pasta should have a small white line in the center. To check just bite the pasta in half.
In a medium saucepan over medium heat melt the butter. Once the butter is melted add the flour salt, pepper and nutmeg.
Using a whisk, whisk the mixture off and on until it is cream in color and has a slight almond smell.
Whisk at a brisk pace while adding the half and half. Add all the cheese except the 1 1/2 cups you reserved for the topping. Blend until smooth. Remove from heat.
Combine the cheese sauce with the past and pour that into your baking dish. Sprinkle the remainder of the cheese on top.
Bake for around 25 minutes. The top should be golden and bubbly.