Baked Macaroni and Beef

First meal is a lean meat and tomato sauce macaroni bake. It was rather good, though we think it could use a little bell pepper.
So far Tony's losing weight. He started a food calorie diary about a week ago and has already lost 5.5 lbs. See the tracker at the bottom of the blog to watch his progress (it rounds to the next full number). We're off to a good start; wish us luck!

Ingredients (serves 6)
1/2 pound extra-lean ground beef
1 small onion, diced, about 1/2 cup
1 box (7 ounces) whole-wheat elbow macaroni
1 jar (15 ounces) reduced-sodium spaghetti sauce
6 tablespoons Parmesan cheese

Preheat the oven to 350 F. Lightly coat a baking dish with cooking spray.
In a nonstick frying pan, cook ground beef and onion until the meat is browned and the onion is translucent. Drain well.
Fill a large pot 3/4 full with water and bring to a boil. Add the pasta and cook until al dente, 10 to 12 minutes. Drain the pasta thoroughly.
Add the cooked pasta and spaghetti sauce to the meat and onions. Stir to mix evenly. Spoon the mixture into the prepared baking dish. Bake until bubbly, about 25 to 35 minutes.
Divide the spaghetti among individual plates. Sprinkle each with 1 tablespoon Parmesan cheese.

EDIT 07/09/11: Added recipe.