Squash Casserole

Cook first 3 ingred in boiling water to cover in a Dutch oven 10 to 12 min or just until tender; drain well in a colander, gently pressing squash mixture against sides w/ a wooden spoon. Stir together squash mixture, Cheddar cheese and next 5 ingred. Spoon into a lightly greased 6 qt. oval shaped slow cooker. Sprinkle w/ Parmesan cheese over top. Cover and cook on low 2 1/2 to 3 hoursor until center is set and edges are golden brown; uncover and cook 30 min. Let stand 10 min. Note: Yellow squash, zucchini and onions may be cooked and drained as directed up to 2 days ahead. Cover and chill until ready to assemble casserole.