How to Make It
Combine ricotta, 2 tablespoons Asiago cheese, 1 tablespoon parsley, 1 tablespoon. chives, pepper, and 1 garlic clove, grated, in a bowl; set aside.
Bring 6 cups water to a boil in a large skillet; stir in red wine vinegar. Add squash and zucchini; cook 2 minutes. Drain.
Heat skillet over medium-high. Coat pan with cooking spray. Add sausage; cook 7 minutes, stirring to crumble. Stir in onion; cook 8 minutes or until onion is tender.
Heat oil in a large saucepan over medium-high. Add mushrooms; cook 10 minutes or until mushroom liquid nearly evaporates. Mince remaining 5 garlic cloves; stir into mushrooms. Stir in stock, basil, and marinara. Bring to a boil; remove from heat.
To assemble lasagna, spoon 1 cup marinara mixture into the bottom of a 6-quart slow cooker. Top with 4 noodles, breaking noodles to fit cooker. Layer half of squash mixture, half of sausage mixture, and ¼ cup fontina cheese over noodles; top with 1 cup marinara mixture. Arrange 4 noodles over marinara mixture; top with ricotta mixture. Sprinkle with ¼ cup fontina; top with remaining half of sausage mixture and remaining half of squash mixture. Arrange remaining 4 noodles over squash mixture; top with remaining 1 ½ cups sauce. Cover and cook on LOW 4 hours.
Preheat broiler. Uncover slow cooker, and sprinkle lasagna with remaining ¼ cup fontina cheese and remaining 2 tablespoons Asiago cheese. Broil on middle rack of oven for 2 minutes or until cheese browns slightly. Sprinkle with remaining 1 tablespoon parsley and remaining 1 tablespoon chives. Let stand 10 minutes before serving.