6 Tbs. (3 oz.) butter
1 qt. milk
3/4 cup flour
2/3 cup shredded Parmesan
4 slices white American cheese
1⅓ cup shredded cheddar
1⅓ cup shredded Gouda
2/3 cup heavy cream
Salt and pepper to taste
4 cups cooked pasta of choice
Preheat oven to 375°F.
In a six-quart stockpot, melt the butter over low heat. Be careful not to brown. Warm the milk in a separate pot while the butter melts. Whisk the flour into butter until smooth and cook for three minutes, stirring occasionally.
Raise the heat to medium. Slowly add the milk, while whisking vigorously to avoid lumps. Stirring frequently, cook until thickened. Turn off the heat and whisk in cheeses, one at a time.
In a large mixing bowl, combine the cooked pasta and cheese sauce and transfer mixture to an oven-safe, three-quart casserole dish. Cover with foil and bake for 30 minutes. Remove the cover and continue baking until the top is golden brown, approximately 10 minutes.