Preheat oven to 350°F. Line a large baking pan with foil, set aside.
In a large mixing bowl, combine the ground beef, onion, bell pepper, eggs, crushed Ritz crackers, cheese, milk, salt, and black pepper.
Use your hands or a wooden spoon to mix well until everything is combined.
On the prepared baking pan, form the meat into a loaf shape. Place the baking pan into the preheated oven for 30 minutes.
While the meatloaf is baking, in a medium mixing bowl, combine ketchup, brown sugar, and mustard. Set aside.
After 30 minutes in the oven, remove the meatloaf from the oven and spread the ketchup glaze all over the top of the meatloaf.
Place the meatloaf back into the hot oven. Bake for another 40 minutes. The meatloaf will be cooked through and the internal temperature will be 160°F Remove from oven and let rest for 10 minutes.
Slice and serve!