In a large skillet, cook the sausage over medium-high heat until brown, breaking up the meat as it cooks.
Stir in Dei Fratelli Marinara Sauce, Dei Fratelli Chopped Italian Tomatoes, mushrooms, and garlic. Remove from heat.
Lightly coat the inside of a 4 quart slow cooker with non-stick cooking spray.
Place 1 heaping cup of meat sauce in the bottom of the slow cooker. This will allow the bottom layer of noodles to properly cook.
Break up pieces of lasagna noodles to make a full layer over the sauce. Top with 1/3 of the ricotta cheese, followed by another heaping cup of meat sauce, and then topped with 1/3 of the shredded Italian cheese blend.
Repeat the process two more times, starting with the noodles, until you have three layers of lasagna.
Cover and cook on high for 3 hours or until top layer of cheese is melted and golden.