Finely dice the onion into 1/4-inch pieces and mince the garlic, setting them aside. Break the lasagna noodles into 1-2 inch pieces and set aside. Shred the mozzarella cheese fresh if not already done, and have the ricotta, parmesan, and fresh basil ready for later steps. Heat 1.5 tablespoons of olive oil in a large pot over medium heat until shimmering, then add the diced onion and cook for 2-3 minutes, stirring occasionally, until it becomes translucent and fragrant. Add the minced garlic and cook for another minute, stirring constantly to prevent burning.

Increase heat to medium-high and add the 1 lb of Italian sausage to the pot with the aromatic base. Break it apart with a wooden spoon as it cooks, allowing it to brown evenly for 5-7 minutes. I like to let the meat develop a nice golden crust on the bottom of the pot before stirring—this creates more complex flavor. Once the sausage is fully cooked and no pink remains, carefully pour off excess grease if needed, leaving about 1 tablespoon to flavor the broth.

Add the 32 oz chicken stock, 30 oz diced tomatoes (with their juice), and 6 oz tomato paste directly to the pot with the sausage mixture. Stir well to dissolve the tomato paste and incorporate all ingredients evenly. Bring the mixture to a boil over medium-high heat, then reduce to a medium simmer. The tomato paste needs thorough incorporation to prevent lumps and ensure even flavor distribution throughout the broth.

Stir in 1 tsp oregano, 0.75 tsp Italian seasoning, and half of the fresh basil (about 2 tbsp), reserving the remaining basil for garnish. Taste and adjust seasoning with salt and pepper as needed. Bring the broth back to a rolling boil, then add the broken lasagna noodles. I find breaking the noodles into smaller pieces creates a heartier, more soup-like texture that's perfect for serving a crowd—much better than leaving them whole.

Once the broth returns to a boil after adding noodles, reduce heat to medium and cook for 8-10 minutes, stirring occasionally, until the lasagna pieces are tender but not mushy. The noodles will continue to soften slightly as they sit, so err on the side of al dente. Remove from heat and stir in the 0.75 cup parmesan cheese and 1.25 cup freshly shredded mozzarella cheese, stirring until completely melted and incorporated. The residual heat will melt the cheese beautifully without requiring additional cooking.

Ladle the hot lasagna soup into bowls. Top each serving with a generous dollop of ricotta cheese (about 1-2 tablespoons per bowl) and sprinkle with the reserved fresh basil. The cool ricotta creates a creamy contrast to the hot, savory broth while the fresh basil adds brightness to the dish.