I actually got the recipe from a great book, Trisha Yearwoods "Georgia cooking in an Oklahoma Kitchen", (this book is worth buying or a great gift idea!)
this is my version:
1 pound macaroni (I used whole wheat penne)
6 tablespoons (1/2 stick) stick butter
4 tablespoons all purpose flour
1 teaspoon salt
2 cups milk
2 cups grated cheddar cheese
grated Parmesan cheese
preheat oven to 350
butter a 2 quart casserole dish
while noodles are cooking, make the cheese sauce.
Melt butter in saucepan. Using a wire whisk, stir in flour and salt. Keep stirring until flour mixture turns pale brown, approx. 3 minutes. Remove from heat and mix in 1 cup of milk. Return to heat and and whisk in remaining 1 cup of milk. continue to cook, stirring constantly, until the sauce thickens. (Be patient!) add the cheese and stir until it melts.
Mix noodles in cheese sauce, pour into prepared pan. top with Parmesan cheese and bake until crispy! (approx. 45 minutes)