Preheat your oven to 425F.
Cut the butternut squash in half, scoop out the cubes, and place the halves in a 9×16 casserole dish. Cut the top off of the garlic bulb, peel the onion and cut it into quarters, and add them to the dish.
Add the tomatoes, spinach and thyme. Drizzle them with olive oil and add salt and pepper to taste. Roast them in the oven for 45-50 minutes.
Once the vegetables and herbs are done roasting, carefully scoop the flesh out of the butternut squash and add it to a blender or food processor. Discard the peel and the thyme, and add the roasted tomatoes, spinach, and onion to the blender. Squeeze the roasted garlic cloves out from the bulb and add them to the blender.
Add the vegetable broth to the blender, and blend the soup until it’s smooth and creamy. You can also use an immersion blender if you have one.
Once it’s blended, add the soup into a large pot or a dutch oven on medium-low heat and stir in the cream. If the soup is too thick, feel free to add more milk or broth until you reach the desired consistency. Add more sea salt and ground black pepper to taste.
Serve the soup hot with some crusty bread or crackers, and top with fresh herbs and pumpkin seeds if desired.