Here's mine--
melt 1/2 cup butter, margarine, or Smart Balance (not the light Smart Balance, too much water)
Suate 1/2 c chopped onion in the melted butter
whisk in 1/2 cup flour until smooth, take off heat
stir in 3 1/2 cups milk
add 16 oz cheddar cheese, I use shredded, it melts faster
then add 1-2 tsp worchestchestire (sp) sauce
boil up macaroni noodles, I do 2 8 oz pkg, drain, add cheese mixture
sprinkle with parmesean cheese, I like the fresh kind
spray baking pan with no-cook spray
bake 375 for about 30 min until bubbly and a little brown on edges
If you like, add sliced tomatoes last 5 minutes of baking
You can also add chopped hot dogs, olives, or ham to the mixture
My kids love it! I always make 2 pans, it goes fast