Preheat your oven to 350 degrees Fahrenheit.
Line a large baking dish with aluminum foil or lightly grease a loaf pan.
In a small bowl, mix the ketchup, brown sugar, and mustard.
Set this mixture aside to use as the topping later on.
In a large mixing bowl, combine the ground beef, eggs, milk, crushed Ritz crackers, onion, bell pepper, salt, and black pepper.
Make sure you mix these ingredients thoroughly using your clean hands for the best results.
Add the shredded cheddar cheese to the mixing bowl and blend it into the meat mixture evenly.
Shape the meat mixture into a loaf and place it in the prepared baking dish.
Bake the meatloaf at 350 degrees Fahrenheit for 30 minutes.
Remove it from the oven, spread the ketchup topping evenly over the loaf, and bake for an additional 20 minutes.