Step 1: Heat olive oil in a large Dutch oven or pot over medium-high heat. Add the Italian sausage, breaking it up with a spoon, and cook until browned and no longer pink, about 6-8 minutes. Drain excess fat and set the sausage aside, leaving about 1 tablespoon of drippings in the pot.
Step 2: Add the diced onion, carrots, and celery to the pot. Sauté for 8-10 minutes, or until the vegetables are softened. Add the minced garlic, Italian seasoning, and red pepper flakes (if using) and cook for another minute until fragrant.
Step 3: Pour in the chicken broth and diced tomatoes. Bring the mixture to a simmer, scraping up any browned bits from the bottom of the pot. Stir in the chopped sun-dried tomatoes.
Step 4: Add the gnocchi to the simmering soup. Cook according to package directions, usually 2-3 minutes, or until they float to the surface.
Step 5: Reduce the heat to low. Stir in the cooked sausage, heavy cream, and fresh spinach. Cook for another 2-3 minutes, or until the spinach has wilted.
Step 6: Remove from heat and stir in the 1/2 cup grated Parmesan cheese. Season with salt and freshly ground black pepper to taste.
Step 7: Ladle the Sausage Gnocchi Soup with Sun-Dried Tomatoes into bowls. Garnish with additional Parmesan cheese and fresh basil or parsley before serving. Enjoy this comforting Sausage Gnocchi Soup with Sun-Dried Tomatoes!