Cheeseburger Chowder

Name: Cheeseburger Chowder
Ingredients: 1 pound ground beef; 1 tablespoon vegetable or canola oil; 1/2 cup chopped onion; 1/4 cup chopped celery; 2 tablespoons chopped green bell pepper; 2 medium potatoes 2 cups, peeled and cubed; 1 tablespoon instant beef bouillon granules; 1 1/2 cups water; 1/2 teaspoon ground black pepper plus more if needed; 3 tablespoons all-purpose flour; 2 1/2 cups whole milk divided; 1 1/2 cups grated sharp Cheddar cheese 6 ounces; Salt; Additional grated sharp Cheddar cheese for garnish