In the slow cooker, combine the dried lentils, onion, garlic, crushed tomatoes, tomato sauce, diced tomatoes, stock, dried basil, dried parsley, red pepper flakes, salt, and flax seed (if using). Stir to combine.
Cover and cook in the slow cooker for 3-4 hours on high or 7-8 hours on low.
When you are about ready to serve, break the lasagna noodles into one inch pieces (they will expand a lot when cooked). Cook the noodles in boiling water on the stove until al dente as per package directions, approximately 7-9 minutes.
While the noodles are cooking, make the herbed ricotta by combining the ricotta cheese, fresh parsley, fresh basil. Season to taste with salt and black pepper.
Add the cooked noodles to the soup and let them sit in the soup on warm for 5 minutes for the flavors to combine. If the soup is too thick, add some additional water or stock until you reach your desired consistency. Season to taste with salt, black pepper, or red pepper flakes.
Serve with the herbed ricotta, Parmesan, mozzarella, or cheese of choice.
Skip the cheese and use vegan noodles for a vegan soup.Easily switch out the broken lasagna noodles for any shaped pasta.Make cleaning easy with slow cooker liners! Grab some here! I get ground flax seed in the bulk bin of my local market, but you can also find it in the baking aisle or online here. I like to add it to all of my soups and sauces for the added health benefits.