Instructions:
- In a large skillet, brown the ground beef and Italian sausage over medium-high heat. Drain off excess grease thoroughly.
- Add the diced onion to the skillet and cook until softened (about 5 minutes). Add the minced garlic and cook for 1 minute until fragrant.
- Transfer the meat and onion mixture to the slow cooker insert. Add the crushed tomatoes, tomato sauce, beef broth, basil, oregano, thyme, salt, pepper, and red pepper flakes (if using). Stir well to combine.
- Cover the slow cooker and cook on LOW for 6 hours or HIGH for 3.5 hours.
- About 30 minutes before the soup is done simmering, mix the ricotta cheese, egg, Parmesan cheese, and fresh parsley together in a bowl. Set aside.
- Increase the heat setting on the slow cooker to HIGH (if it was on LOW). Stir in the broken lasagna noodles. Cook, uncovered, for 15-20 minutes, stirring occasionally, until the noodles are al dente.
- Remove the lid. Dollop spoonfuls of the ricotta mixture directly into the hot soup. Gently swirl them in, but do not fully incorporate them to maintain distinct pockets of cheese.
- Sprinkle the shredded mozzarella evenly over the top of the soup. Cover and let sit on the WARM setting (or remove from heat) for 5-10 minutes until the mozzarella is melted and bubbly.
- Ladle into bowls, ensuring everyone gets a good swirl of ricotta, and top with extra Parmesan and fresh parsley before serving.