Preheat oven to 350 degrees. In a large bowl mix vegetables, cheese, onions, and soup, with salt and pepper to taste. (I tend to go heavier on the cheese because my kids eat it better.) Put in sprayed 9″ x 9″ square dish. Spread flat and top with french fried onions. (Remember only 1 for taste testing for the one making it!) Cover with foil and bake for about 30-45 minutes.
Time depends on oven and how many other dishes are cooking with it. You will have to check to see that cheese is melted in vegetables. Remove foil for the last 10 minutes of cooking to brown. Remove from oven and serve.