Place a large Dutch oven or heavy-bottomed pot over medium-high heat. Add the Italian sausage and cook, breaking it up with a wooden spoon, until it is browned and cooked through. Drain any excess grease, leaving about a tablespoon in the pot for flavor.

Add the diced onion to the pot with the sausage. Sauté for about 5 minutes until the onion is soft and translucent. Stir in the minced garlic and cook for another 60 seconds until fragrant, being careful not to let the garlic burn.

Stir in the tomato paste and cook for 2 minutes to deepen the flavor. Add the crushed tomatoes, broth, Italian seasoning, and red pepper flakes. Bring the mixture to a boil, then reduce the heat to a simmer. Season with salt and pepper to taste.

Add the broken lasagna noodles directly into the simmering soup. Cook according to the package directions, usually about 10 to 12 minutes, stirring occasionally to prevent the noodles from sticking to the bottom of the pot. Ensure the noodles are al dente.

While the soup simmers, use a small ghost-shaped cookie cutter (or a knife) to cut shapes out of the mozzarella slices. Use small pieces of black olives or peppercorns to create little eyes on your cheese ghosts.

Once the noodles are tender, turn off the heat. Ladle the hot soup into bowls. Place a dollop of ricotta cheese in the center of each bowl, then carefully set a mozzarella ghost on top. The heat from the soup will slightly melt the ghost, making it look extra spooky. Garnish with fresh parsley and serve immediately.