In a large pot or Dutch oven, brown the Italian sausage over medium heat, breaking it up with a spoon. Drain off any excess grease.

Add the olive oil, onion, and garlic to the pot. Cook until the onion is softened, about 5 minutes.

Pour in the chicken broth and diced tomatoes. Bring to a boil, then reduce heat and simmer for 15 minutes.

Stir in the acini di pepe pasta and cook until tender, about 8-10 minutes.

Add the spinach and cook until wilted, about 1-2 minutes.

Season with salt and pepper to taste.

Serve hot, garnished with grated Parmesan cheese.