3 parsnips, peeled and cut into 1/2-inch pieces
3 carrots, peeled and cut into 1/2-inch pieces
1 celery root, peeled and cut into 1/2-inch pieces
2 turnips, quartered
1 sweet potato, peeled and cut into 1/2-inch pieces
1 (2 pound) butternut squash, peeled and cut into 1/2-inch pieces
1/4 cup olive oil
1 teaspoon kosher salt
1/2 teaspoon ground black pepper
3 tablespoons butter
1 stalk celery, diced
1/2 sweet onion, diced
1 quart vegetable broth
1/2 cup half-and-half cream
salt and ground black pepper to taste