Tortellini Soup with Italian Sausage, Spinach and Tomatoes

Bahan-bahan (6 porsi)

• 1 pound ground hot Italian sausage
• 1 tablespoon olive oil
• 1 cup diced white onion (about 1 small white onion)
• 5 cloves garlic, minced
• 1 (28-ounce) can fire-roasted crushed tomatoes
• 6 cups chicken or vegetable stock
• 1/4 cup roughly-chopped fresh basil leaves, loosely-packed
• 1 teaspoon salt
• 1/2 teaspoon black pepper
• 1 package (about 1 pound) tortellini, refrigerated or frozen (*or 1 package of dried tortellini cooked according to package instructions)
• 2 cups fresh baby spinach, packed
• freshly-grated Parmesan cheese, for serving