Cook pasta according to package directions, omitting salt and fat. Drain; set aside.
Melt 1 tablespoon margarine in a medium heavy saucepan over medium-high heat. Add onion and garlic; sauté 5 minutes or until tender. Add flour; cook 30 seconds, stirring constantly. Gradually add milk; cook 4 minutes or until bubbly. Remove from heat. Stir in 1/4 cup cheese, Italian seasoning, and pepper; remove from heat.
Combine pasta, cheese sauce, 1 cup cheese, tomatoes, and spinach in a large bowl; stir well. Spoon mixture into a 13 x 9-inch baking dish coated with cooking spray.
Combine breadcrumbs, 2 tablespoons cheese, and remaining 1 tablespoon margarine; sprinkle over pasta mixture. Bake at 350° for 30 minutes or until thoroughly heated. Garnish with parsley, if desired.
I've also been making this for years! Perfect meatless main dish - excellent and filling. It can be made a day or two ahead, and also freezes well if you want to freeze half. (In my house half easily serves 2-3 adults, especially if there is also bread and salad.)
Have been making this recipe since it came out in 1997. It can be time-consuming but with some planning (cook pasta while making sauce) it can still be on your table in an hour. Great with whole wheat or regular pasta, and usually I use penne since it's easier to find. I use a little less milk for a clingy-er parmesan sauce, and I add salt to the sauce since I typically use "no salt added" tomatoes. Green salad, and you've got yourself a meal! 9 WW points per serving (using new 2011 program).
Very delicious. Takes awhile to make but definitely worth it. I used a shallot and an onion but then followed the recipe exactly. (Well, I did use a lot more cheese than called for.) My husband and I loved it and it's even better left over and reheated. Served it with a fruit salad.