HEAT oven to 350ºF.
PIERCE squash with fork several times. Microwave on HIGH 15 min. or until tender when pierced with knife.
MEANWHILE, brown meat in large skillet; drain. Return to skillet. Stir in spaghetti sauce and 1/2 tsp. seasoning; bring to boil. Simmer on medium-low heat 5 to 8 min. or until slightly thickened.
CUT squash in half; remove seeds. Scrape squash into large bowl. Add flour; toss to coat. Add butter, eggs, Parmesan and garlic; mix lightly. Spoon into 10-inch pie plate sprayed with cooking spray; top with meat sauce, leaving 1/2-inch rim around edge. Top with shredded cheese and remaining seasoning.
BAKE 30 to 35 min. or until squash mixture is heated through and cheese is lightly browned.