This is the mac and cheese I have been making since Day One, meaning the day I learned to cook. The recipe most likely came from an old BH&G cookbook, because I don't remember my mother ever making mac and cheese. This has been a favorite in my family for years because it is so creamy throughout and crispy on top.
Cook macaroni according to package directions; drain and set aside.
Melt butter in a medium saucepan over medium heat; blend in the flour, salt and pepper. Add milk gradually, stirring constantly until thickened and bubbly. Turn off heat.
Add onion (optional) and 1-1/2 cups of the cheese. Stir until cheese is melted.
Mix the cheese sauce with the drained macaroni in a separate large bowl until macaroni is completely coated with sauce. Turn mixture into a 2-qt. casserole dish which has been sprayed with cooking spray. Sprinkle remaining cheddar cheese over the top and bake in a preheated 350-degree oven, uncovered, for 45 minutes or until golden brown and bubbly.
NOTE: For a creamier dish, use half-and-half instead of milk.