Instant Pot Butternut Squash Soup

pancetta, cut into 1/2-inch pieces

large sage leaves, minced

medium carrots, cut into 1-inch pieces

stalk celery, cut into 1-inch pieces

medium onion, cut into 1-inch pieces

ground cumin

Kosher salt and freshly ground black pepper

butternut squash cut into 1-inch pieces (from a 2-pound squash)

chicken stock

cream, optional

small white button mushrooms, stems trimmed and cut into 1/8-inch slices

ground cumin

Kosher salt

Creme fraiche or full-fat Greek yogurt, thinned to a pourable consistency with 1 to 2 tablespoons water 

Minced fresh chives