In a cast iron skillet over medium-high heat, cook the sausage until browned. While the sausage is cooking, add in the diced onion and minced garlic.
In a large Dutch oven, stir together the tomato paste, marinara sauce, and Italian seasoning.
Add the browned sausage and chicken broth to the pot and bring everything to a boil.
Once boiling, add the lasagna noodles (broken into 3–4 pieces each). Reduce the heat to medium-low and cook, stirring occasionally, until the noodles are tender. Around 10 minutes.
Once noodles are cooked, remove from the heat and stir in spinach.
In a small bowl, mix together the ricotta, mozzarella and Parmesan cheeses.
Serve the lasagna soup hot and top each bowl with a generous scoop of the cheese mixture.
Notes
Add salt and pepper to taste! I use ground Italian pork sausage, and it already has plenty of seasonings. If you swap it out with ground beef or use unseasoned sausage, you may want to add some salt and pepper.
I don't drain the meat before adding it to the Dutch oven. If you have a lot of grease or if you use ground beef, you'll definitely want to drain off some of the excess grease.
You can use any marinara sauce you like, but I really recommend using a plain, organic option. Flavored sauces—those with cheese or meat already in them—can interfere with the final taste of your soup.
If whole grains are your thing, try swapping out the packaged pasta with homemade whole wheat noodles! You can cut them wider to make lasagna noodles.
For an even creamier soup, you can add a splash of heavy cream or half and half to the broth.