Cheesy Carrot Casserole

Name: Cheesy Carrot Casserole
Cuisine: American
Ingredients: 3 Tablespoons butter (salted); 1 medium onion, chopped; 4 Tablespoons flour; ½ teaspoon salt; ½ teaspoon pepper; 1 cup milk; ½ cup cream; 2 cups cheddar cheese, shredded; 3½ cups carrots, sliced and cooked until just tender; 1 Tablespoon dried parsley flakes; 2 cups cornflakes; Large pot or Dutch oven; Medium bowl; 9×11 baking dish; Cooking spoon or spatula