Busy families, this recipe is for you. I crave the comfort of homemade lasagna in the winter, but I dislike the lengthy assembly time that often accompanies the dish. The slow cooker makes the entire process really simple: no boiling noodles, no precooking the vegetables and no need to worry about making neat layers.
Lightly spray the inside of a slow cooker crock with nonstick cooking spray. Spread 1/2 cup marinara sauce on the bottom of the slow cooker, then add a layer of noodles (you may have to cut or break noodles to fit in a single layer).
Cover the noodles with 3/4 cup ricotta cheese, 1/4 cup green peas, 1 cup baby spinach leaves, 1 cup sliced zucchini and 3/4 cup marinara sauce. Repeat with two additional layers of noodles, ricotta, vegetables and sauce; you will have three layers in all. End with a final layer of noodles, the remaining marinara sauce and the mozzarella cheese.
Cover with the lid and cook on high for 3 hours or 5 to 6 hours on low. Turn the slow cooker off and let the lasagna sit for at least 30 minutes before serving (this allows it to firm up).