Combine onion and margarine in a 2-quart glass measure or casserole. Cover with vented plastic wrap or lid. Microwave on high 5 1/2 to 6 1/2 minutes. Remove onion with a slotted spoon and place in bottom of pie shell. Stir flour into cheese and sprinkle over top of onion. Place tomatoes on top of cheese.

To liquid remaining in measure, add milk, eggs and Italian seasoning; beat well. Pour milk mixture over ingredients in pie shell. Rotating midway through cooking, microwave on medium-high (70%) 10-12 minutes, or until center is almost set. Let stand 10 minutes before cutting.

Nutrient data per serving: 475 calories; 19 grams protein; 31 grams fat (59% of total calories); 28 grams carbohydrates; 2 grams dietary fiber; 132 milligrams cholesterol; 309 milligrams sodium.