Preheat oven to 375 degrees. Grease a 9x11 casserole pan (or cake pan if you don't have a glass casserole dish). Prepare macaroni according to package directions. Melt butter in saucepan over medium heat until melted. Next, whisk in the flour. Continue whisking and cooking for 2 minutes until butter/flour mixture turns light golden brown. Slowly add the milk. Cook until the sauce thickens, about 10 minutes, stirring frequently. Remove from the heat. Add 3 C. Cheddar cheese, Monterrey Jack cheese, salt, chile powder and garlic powder. Stir until the cheese is melted and all ingredients are incorporated.
Blend cheese and elbow noodles and place in a greased 9x11 casserole dish. Top with additional Cheddar cheese and bake for 45 minutes or until bubbly.
Recipe by Frugal Bites at http://frugalbites.com/best-ever-macaroni-and-cheese-recipe/