Made with canned tomatoes, dried seasonings, and lentils that plump up in the rich tomato broth, this easy vegetarian lasagna soup is the perfect way to warm up on a cool night! Let it simmer all day and come home to a big bowl of tomato-y goodness you can enjoy ASAP. Plus, it’s perfect for meal prepping and can makes the easiest freezer meal ever! {Vegetarian, Vegan, & Dairy-Free-Friendly}
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Slow Cooker Vegetarian Lasagna Soup
We’re always looking for ways to eat delicious meals without a lot of hands-on time or effort, and this vegetable lasagna soup is a real winner. Not only does it have all the flavors of classic lasagna, but it’s made using mostly ordinary pantry staples, so we can throw it together anytime.
Plus, it’s packed with fiber, plant-based protein, and essential vitamins and minerals to support the health of the whole family. It’s on our regular menu rotation!
If you’re a lasagna lover, you’ll also want to check out this No Ricotta Lasagna and Ground Turkey Zucchini Lasagna!
Why We Love This Vegetarian Lentil Lasagna Soup
- Dietitian-designed to be nutritionally balanced with plenty of protein and fiber
- Tastes like traditional lasagna…in soup form!
- Kid-friendly flavors the whole family will love
- Vegetarian version of my lazy lasagna soup to accommodate the whole family
- Can be prepared ahead of time as a freezer meal for those busy times of year
- Makes a big pot for plenty of leftovers
- Only requires 10 minutes of active effort
- Cooks in the slow cooker all day for an easy meal at night
Ingredient Notes
- Canned San Marzano tomatoes: These are the real deal and have the very best tomato flavor. You can typically found them in the aisle with the other canned tomatoes.
- Aromatics: Dice a yellow onion and mince fresh garlic gloves for fresh flavor.
- Tomato paste: This has a concentrated tomato flavor and adds umami to the soup, making it satisfying and hearty even without meat.
- Seasonings: I used dried basil, dried oregano, kosher salt, freshly cracked black pepper. You can certainly adjust the salt to taste to keep it low sodium and feel free to swap Italian seasoning blend for the dried herbs.
- Marinara sauce: I used Rao’s, which has a wonderful flavor and minimal sugar.
- Green or brown lentils: Either option works well. Red lentils taste great, but they cook faster and are more prone to disintegrating during the long cook time.
- Vegetable broth: This is the base of the soup. Look for low sodium broth or make your own from veggie scraps!
- Lasagna sheets: You need broken lasagna noodles that can be picked up with a spoon. I used whole wheat pasta noodles for extra fiber to make this soup even more filling.
- Optional toppings: There are lots of options! Add a dollop of ricotta cheese or small curd cottage cheese, shredded mozzarella, parmesan cheese, and/or fresh basil.
Step-by-Step Instructions
- Place the San Marzano tomatoes in a 6+ quart slow cooker and mash with a potato masher or puree with an immersion blender.
- Place all of the ingredients in the slow cooker. Place the lid on and cook on low 6-8 hours, or on high for 4 hours. Add the noodles during the last 30 minutes of cooking. Stir halfway through.
- Once the noodles are tender, taste and adjust seasoning. Serve hot topped with cheese and fresh basil.
Keep scrolling to the recipe card below for the full printable recipe!
Expert Tips
- This soup will thicken significantly as it cools. You may choose to add a splash of broth or water before reheating to loosen it back up, or enjoy it as is!
- You can add in 5 ounces of fresh spinach during the last 15 minutes of cooking if desired. Sautéed mushrooms or diced zucchini make a great addition during the last 15 minutes as well.
- Mini lasagna noodles (mafalda corta) or campanelle are great substitutes for breaking up full lasagna noodles.
- We developed this recipe using Rao’s brand marinara sauce. This sauce is made with high quality tomatoes and ingredients and has very low sugar. You can substitute this with your favorite marinara. Adding a half jar of marinara to the soup helps give the soup a big flavor burst with minimal effort!
- Feel free to use gluten-free pasta to make this soup gluten-free.
Recipe FAQs
San Marzano tomatoes are imported from Italy, and are readily available at most grocery stores. Be sure to read the label and choose imported San Marzano tomatoes, not San Marzano style tomatoes. They are naturally sweet with very low acidity, which makes them perfect for soups and sauces. They cost a little bit more than other canned tomatoes, but are far superior in quality and make a world of difference in the final product.
Any canned tomato can be substituted for San Marzano if you can’t find them. If the final soup is too acidic, try adding ¼ teaspoon baking soda during the last half hour of cooking to neutralize some of the acid.
Although the ingredients for this vegetarian lasagna soup can be frozen ahead of time, I don’t recommend freezing the leftovers! The cooked pasta will soften and become soggy after thawing and reheating, which isn’t ideal.
The secret to this soup is really the rich tomato sauce. It plumps up the lentils and infuses flavor into every bite. To get that rich flavor without any meat or animal products, you really need to create some body and that comes from the canned tomatoes, tomato sauce, and marinara sauce. It makes a big difference!
Storage Guidelines
To refrigerate: Allow any leftover soup to cool to room temperature, then transfer to an airtight container. Refrigerate for 3-4 days.
To reheat: Warm the leftovers in a pot on the stove until nice and hot or microwave for several minutes. The pasta noodles will soften as they sit in the broth, so they won’t be quite as firm or al dente as before.
For freezer meal prep: Combine all ingredients, except broth and noodles, in a gallon size zip top bag. Remove as much air as possible. Freeze for up to 3 months. When ready to cook, thaw overnight or for 24 hours in the fridge.
Serving Suggestions
This deconstructed lasagna soup is really a whole meal on its own! We do like to serve it with warm garlic bread or another crusty bread to soak up that tasty tomato broth, but that’s all it needs.
To add more veggies, I also like to serve it with a side salad, like this tossed green salad or caesar salad with homemade croutons, for a little contrast and crunch.
Recipe Variations
- Add protein: If you want to keep this dish vegetarian, consider adding a can of drained and rinsed cannellini beans, vegan sausage, or a ground beef meat alternative. If your family eats meat, you can brown Italian sausage and/or cooked ground beef to add to the soup. Very hearty!
- Add more veggies: You can really go wild with fresh veggies here, if you’d like! Sautee some mushrooms, zucchini, bell peppers, or eggplant to soften in the rich tomato broth. You can also add a bag of frozen spinach or kale for extra greens.
- To keep it vegan: This vegan lasagna soup recipe contains no dairy products on its own, but it can be helpful to know some plant-based dairy substitutes for the toppings. Look for vegan cheese, like shredded Parmesan or vegan ricotta cheese, for a creamy texture that makes the whole soup more satisfying.
More Delicious Soup Recipes
- Spiced Carrot and Lentil Soup
- Slow Cooker White Bean Soup Recipe
- Mexican Garbanzo Bean Soup
- Roasted Butternut Squash and Carrot Soup
- Slow Cooker Loaded Baked Potato Soup
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Easy Vegetarian Lasagna Soup {Slow Cooker}
Ingredients
- 28 ounce can San Marzano tomatoes
- 1 small yellow onion, finely diced
- 3 large garlic cloves, minced
- 2 tablespoons tomato paste
- 1 teaspoon dried basil
- 1 teaspoon dried oregano
- 1/2 teaspoon kosher salt
- 1/2 teaspoon freshly cracked black pepper
- 14 ounces (half a jar) marinara sauce (I use Rao's)
- 1/2 cup green or brown lentils
- 6 cups vegetable broth
- 8 lasagna noodles, broken into bite size pieces (I used whole wheat)
Optional Toppings
- Optional toppings: ricotta or small curd cottage cheese, shredded mozzarella, parmesan cheese, fresh basil
Instructions
- Place the San Marzano tomatoes in a 6+ quart slow cooker and mash with a potato masher or puree with an immersion blender.
- Place all of the ingredients in the slow cooker. Place the lid on and cook on low 6-8 hours, or on high for 4 hours. Add the noodles during the last 30 minutes of cooking. Stir halfway through.
- Once the noodles are tender, taste and adjust seasoning. Serve hot topped with cheese and fresh basil, if desired.
Notes
- This recipe makes about 8-10 cups. The nutritional information is based on about a 1 1/2 cup serving. The optional cheese and toppings are not included in the nutritional breakdown. Adding some cheese on top is a good way to add some extra protein.
- You can add in 5 ounces of fresh spinach during the last 15 minutes of cooking if desired. Sautéed mushrooms or diced zucchini make a great addition during the last 15 minutes as well.
- This soup will thicken significantly as it cools. You may choose to add a splash of broth or water before reheating to loosen it back up, or enjoy it as is!
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