Brown the sausage: Place a large Dutch oven or heavy-bottomed pot over medium-high heat. Add a swirl of olive oil. Once it shimmers, add the Italian sausage. Use a wooden spoon to break it up into small crumbles as it cooks. Let it sizzle and brown, about 5-7 minutes, until it's cooked through and nicely caramelized. Don't drain the fat!

Build your flavor base: Add the chopped onion to the pot with the sausage. Sauté for about 5 minutes, stirring occasionally, until the onion is soft and translucent. Now, add the minced garlic, dried oregano, dried basil, and red pepper flakes. Stir constantly for about one minute until the air fills with the most incredible fragrance.

Add the tomato foundation: Spoon in the tomato paste and stir it into the sausage and onion mixture. Let it cook for another minute or two. You'll notice it darkens slightly in color. This little step deepens the tomato flavor and adds a beautiful richness to the broth.

Simmer the soup: Pour in the crushed tomatoes and the broth. Give everything a good stir, scraping up any delicious browned bits from the bottom of the pot. Bring the soup to a boil, then reduce the heat to low, cover, and let it simmer for at least 15-20 minutes.

Cook the pasta: Turn the heat back up to medium. Add the broken lasagna noodles directly to the pot. Stir well to make sure they don't stick together. Let the soup gently bubble, uncovered, for about 10-12 minutes, or until the pasta is tender al dente.

Finish and serve: Turn off the heat. Stir in the fresh baby spinach until it just wilts into the hot soup. This only takes a minute. Give it a final taste and season with salt and pepper as needed. To serve, ladle the hot soup into bowls. Top each serving with a generous dollop of ricotta cheese, a sprinkle of shredded mozzarella, and a dusting of Parmesan. Garnish with fresh parsley or basil, and serve immediately.