Mix ground beef, onion, bell pepper, 1 cup Cheddar cheese, Worcestershire sauce, sour cream, and crackers together in a bowl. Place mixture on a baking dish and shape into a loaf.
Bake in the preheated oven until no longer pink in the center, 35 to 40 minutes. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C).
Heat the cream of mushroom soup, milk, and 1 1/2 cup Cheddar cheese in a saucepan over medium heat until the cheese has melted, about 10 minutes. Pour sauce over the meatloaf before serving.
