Heat the olive oil in a large pot or Dutch oven over medium-high heat. Add the Italian sausage and cook, breaking it up with a wooden spoon, until fully browned and no pink remains, about 5 to 6 minutes. Drain off any excess grease.

Add the diced onion to the pot and cook, stirring occasionally, until softened and translucent, about 4 to 5 minutes. Stir in the minced garlic, dried oregano, dried basil, and red pepper flakes if using. Cook for one more minute until fragrant. Watch the heat — garlic burns quickly and turns bitter.

Pour in the chicken broth and the undrained diced tomatoes. Stir to combine and bring the soup to a full boil over high heat.

Add the cheese ravioli directly to the boiling soup. Cook according to package directions for al dente — about 4 to 5 minutes for fresh ravioli or 6 to 8 minutes for frozen. Check early to avoid overcooking.

Stir in the fresh spinach and cook for 1 to 2 minutes, just until wilted.

Reduce the heat to low and stir in the heavy cream. Season with salt and black pepper to taste. Heat gently for 1 to 2 minutes. Do not let the soup boil after adding the cream. Ladle into bowls and top with grated Parmesan cheese before serving.