Step 1: In a large pot or Dutch oven, heat olive oil over medium heat. Add chopped onion and sauté until softened, about 5-7 minutes.
Step 2: Add minced garlic and plant-based Italian sausage (if using) to the pot. Cook, breaking up the sausage, until browned, about 5-8 minutes.
Step 3: Stir in the diced butternut squash, vegetable broth, dried sage, dried thyme, and nutmeg. Bring the mixture to a simmer.
Step 4: Reduce heat to low, cover, and cook for 15-20 minutes, or until the butternut squash is fork-tender.
Step 5: Carefully transfer about 2 cups of the soup mixture (solids and liquid) to a blender and blend until smooth. Alternatively, use an immersion blender directly in the pot to blend about half of the soup for creaminess, leaving some squash chunks. Return the blended portion to the pot.
Step 6: Increase heat to medium-low. Add the gnocchi to the simmering soup and cook according to package directions, usually 2-3 minutes, or until they float to the surface.
Step 7: Stir in the half-and-half and chopped kale. Cook for another 2-3 minutes, or until the kale has wilted.
Step 8: Season the soup with salt and freshly ground black pepper to taste. Ladle into bowls and serve hot, topped with fresh Parmesan cheese if desired.