Heat a large soup pot over medium-high heat. Add the Italian sausage and cook, breaking it up with a spoon, until browned and cooked through. Drain excess fat if needed. :contentReference[oaicite:1]{index=1}

Add the diced onion, celery, and carrots to the pot. Sauté until the vegetables are softened, about 4–5 minutes. :contentReference[oaicite:2]{index=2}

Stir in the minced garlic, Italian seasoning, salt, and pepper. Cook for about 1 minute until fragrant. :contentReference[oaicite:3]{index=3}

Pour in the chicken broth and bring the soup to a boil. Reduce heat to a simmer. :contentReference[oaicite:4]{index=4}

Add the tortellini to the simmering soup and cook according to package instructions (usually 5–7 minutes) until al dente. :contentReference[oaicite:5]{index=5}

Stir in the heavy cream and fresh spinach (if using). Simmer another 2–3 minutes until the spinach wilts and the soup is heated through. :contentReference[oaicite:6]{index=6}