Preheat oven to 350 degrees. Cook yellow squash and onion in boiling water to cover in a large pot 8 minutes or just until the vegetables are tender; drain squash mixture well.
Combine squash mixture,shredded Cheddar cheese, next 5 ingredients, 1 cup bread crumbs and 3/4 cup Parmesan cheese. Spoon into a lightly greased 13 x 9inch baking dish.
Stir together melted butter, french fried onions, and remaining 1 cup breadcrumbs and 1/2 cup Parmesan cheese. Sprinkle over squash mixture.
Bake at 350 degrees for 35 to 40 minutes or until set. ENJOY!