Boil one pound of penne- whole wheat is fine. Dump it into an oven safe container. Saute 12 sliced button mushrooms and 1 chopped onion in 1 tbs. oil for about 10 minutes. Add to the casserole dish along with 1 cup of frozen peas.
Grate about 1/4 pound of mild cheese- jack or mozzarella is good- which will turn into about a cup of grated cheese. Put 2 tbs. flour and 2 tbs. butter or oil into a heavy pot. Heat gently, stirring to combine, until flour smells a little bit like toast and is slightly golden. Grate in a couple of cloves of garlic, using the small side of the grater. Slowly add 1 and 1/2 cups of milk or white wine, whisking to combine. When liquid is about the temperature of hot coffee, add cheese little by little, whisking constantly. Pour complete cheese sauce over pasta and vegetables. Stir to mix. Cover container, and bake at 350 degrees for 30 minutes.
I'm a firm believer that eating lots of vegetables is important enough to justify occasionally drizzling (blanketing) them with cheese sauce. C is a firm believer that pasta and cheese are the best flavor friends ever.