Meatless Monday--Macaroni and Cheese

I love cheese.  I love it so much that I buy cheddar from a restaurant supply store for about $27 for a 10 pound block (which lasts us about 2 months).  Since I tend to buy whole wheat pasta when it is on sale for a dollar, that makes this whole meal, when served with vegetables from a garden (mine or my mom's), a fairly wholesome (although admittedly not diet, since it's pretty high in fat), comforting dinner for the whole family for about $3!

1 1/2 cups uncooked macaroni, penne, or other pasta
1/4 cup butter
1 small onion, diced
1/2 tsp salt
1/4 tsp pepper
1/4 cup all-purpose flour
1 3/4 cup milk
2 cups shredded cheddar cheese

Preheat oven to 375.  Cook pasta according to package directions.  In a separate saucepan,  melt butter and cook onion over medium heat until slightly tender.  Blend in flour, salt, and pepper.  Cook over low heat, stirring constantly, until the mixture is bubbly.  Stir in milk and bring to a boil, stirring constantly.  Boil and stir for 1 minute and remove from heat.  Stir in cheese until melted.  Stir in cooked macaroni.  Pour macaroni and cheese into an ungreased 1 1/2 quart casserole dish.  Bake uncovered for 30 minutes.