How to Make It
Preheat broiler with oven rack in top position.
Heat 2 teaspoons oil in a 10-inch oven-proof skillet over medium-high. Add polenta slices; cook slices 4 minutes on each side or until golden brown. Remove pan from heat.
Heat remaining 2 teaspoons oil in a medium saucepan over medium-high. Add turkey; cook 7 minutes or until browned, stirring to crumble. Add mushrooms, onion, and garlic; cook 6 minutes. Stir in marinara sauce, oregano, and vinegar; cook 5 minutes. Pour turkey mixture over polenta in skillet. Sprinkle mozzarella and Parmesan cheeses over pan. Place pan in oven; broil 2 minutes or until cheese is melted and browned.