Autumn Tortellini Soup With Sausage

Ingredients

• 1 tablespoon olive oil
• 1 pound Italian sausage, casings removed
• 1 medium onion, diced
• 2 cloves garlic, minced
• 2 carrots, peeled and sliced
• 2 stalks celery, sliced
• 1 teaspoon Italian seasoning
• 1/2 teaspoon crushed red pepper flakes (optional)
• 6 cups chicken broth
• 1 (14.5-ounce) can diced tomatoes
• 1 (9-ounce) package cheese tortellini
• 2 cups fresh spinach leaves
• Salt
• black pepper
• Grated Parmesan cheese, for serving
• Fresh parsley, chopped, for garnish