Loaded Chicken Potato Soup

Name: Loaded Chicken Potato Soup
Ingredients: 2.5 pounds russet potatoes; 2 tablespoons olive oil, divided; 1 onion, diced; 1 cup diced carrots; 2 stalks celery, diced; 1 pound skinless, boneless chicken breast halves, cut into chunks; 1 teaspoon salt, plus more to taste; 0.5 teaspoon ground black pepper, plus more to taste; 6 tablespoons butter; 2 tablespoons all-purpose flour; 3 cups milk; 1 cup chicken stock; 1 cup bite-size broccoli florets; 5 ounces shredded sharp Cheddar cheese, divided; 0.5 cup bacon bits, divided; 2 green onions, chopped, divided; 1 cup sour cream