Heat butter and olive oil in a large pot over medium heat. Add butternut squash, potatoes, onion, carrot, celery, and garlic; cook and stir until evenly coated and warmed through, about 10 minutes.

Pour enough chicken broth into the pot to cover the butternut squash mixture. Cook for 10 minutes. Add pear; simmer until potatoes are soft, about 30 minutes. Season with ginger, cayenne pepper, allspice, nutmeg, salt, and pepper.

Fill a blender halfway with soup. Cover and hold lid down with a potholder; pulse a few times before leaving on to blend. Pour into a pot. Repeat with remaining soup.

Stir heavy cream into the blended soup. Cook until heated through, 5 to 10 minutes.