Cook macaroni according to package directions; drain.
For cheese sauce: In a saucepan melt butter or margarine. Cook onion in butter till tender but not brown. Stir in the flour, salt, and pepper. Add milk all at once; cook and stir till thickened and bubbly. Cook and stir 1 to 2 minutes more. Add cheese, stir till melted. Stir macaroni into cheese sauce.
Turn into a 1 1/2 quart casserole. Arrange tomato slices atop macaroni; sprinkle with a little salt.
Bake in a 350°F oven 30-35 minutes or till heated through.
Calories From Fat
% Daily Value*
Total Fat 0g
Saturated Fat 0g
Trans Fat 0g
Dietary Fibers 0g
* Percent Daily Values are based on a 2,000 calorie diet.
* Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin and freshness of ingredients used.