Add flour; stir while cooking, 1-2 minutes.
07Whisk in milk and add garlic.08Season with salt and cayenne pepper.09Stir in cheddar cheese and all but 2 tbs parmesan cheese.10Add potatoes to sauce and stir to mix evenly.11Pour into casserole dish.12Sprinkle remaining parmesan cheese over top.13Bake casserole 45 minutes or until potatoes are tender and dish is bubbling and lightly brown on top.14Let stand 5 minutes before serving.