Meanwhile, for filling, coat an unheated large nonstick skillet with nonstick cooking spray. Preheat over medium heat. Add mushrooms, carrots, and garlic to hot skillet. Cook for 3 to 5 minutes or just until vegetables are tender, stirring occasionally. Remove from heat; cool slightly. Stir in ricotta cheese, 1/2 cup of the mozzarella cheese, the eggs, Parmesan cheese, and Italian seasoning. Spoon filling into cooked manicotti shells.