If you do not have fresh pumpkin puree in your freezer, begin by preparing the pumpkins for baking.
Preheat oven to 350° F
Using a knife, carefully remove the stem piece from each pumpkin.
Next, cut each pumpkin into four pieces then use a spoon to clean out the seeds and stringy pulp. The seeds may be cleaned and saved to use another time.
Place each pumpkin quarter on a foil lined baking sheet and bake for 1 hour.
Allow the pumpkin to cool enough for handling. You can use your fingers to peel away the pumpkin shell skin or use a spoon to remove the cooked pumpkin and set aside until ready to use.
Heat a dutch oven or soup pot over medium
Add the butter and melt
Next, add the diced onion, sliced carrot, sliced celery and minced garlic to the pot and saute for 5 minutes.
Next, add the chicken stock and roasted pumpkin
Season with salt and pepper and add the thyme
Cover the pot and bring the soup to a boil.
Reduce the heat so the soup is simmering and cook for 1 hour.
Remove from heat and use an immersion blender to carefully blend the soup until smooth.
Serve hot with a teaspoon drizzle of heavy cream if desired.