Melt butter in a 6 quart stockpot over medium heat. Sauté onion in butter until translucent, about 8 to 10 minutes. Add carrot and celery and sauté for about 2 to 3 more minutes. Add pears and sauté until soft. Increase heat to medium high and add wine to stockpot.
Deglaze with white wine and cook until most of the liquid has evaporated.
Add pumpkin, chicken stock, and herbs to pot and whisk to combine. Bring liquid to a low boil and simmer for 20 minutes. Remove thyme sprigs. Transfer soup to blender and puree until smooth, working in batches if necessary. Return soup to stockpot. Add cream and season to taste with salt and pepper. Serve immediately.