Creamy Chicken Noodle Soup

Name: Creamy Chicken Noodle Soup
Ingredients: 1 bunch scallions; 1/4 cup unsalted butter; 5 carrots, sliced into 1/4-inch rounds (2 cups); 4 celery stalks, chopped (1 cup); 1/2 teaspoon black pepper, plus more for garnish; 1 1/4 teaspoons kosher salt, divided; 1/4 cup all-purpose flour; 3 tablespoons white miso paste; 1 tablespoon minced garlic (from 3 large garlic cloves); 8 cups homemade or store-bought low-sodium chicken broth; 3 cups (5 ounces) wide egg noodles; 12 ounces cooked chicken, torn into bite-size pieces (3 cups); 1/2 cup heavy whipping cream