Preheat oven to 350°F. Line a baking sheet with foil and spray with cooking spray.
In a large bowl, combine ground beef, onion, bell pepper, crushed crackers, cheese, eggs, milk, salt, and pepper. Mix until just combined.
Shape the mixture into a loaf and place it on the prepared baking sheet.
In a small bowl, whisk together ketchup, brown sugar, and mustard to make the glaze.
Spoon half the glaze over the meatloaf.
Bake for 30 minutes, then top with remaining glaze.
Bake an additional 30 minutes or until the internal temperature reaches 160°F.
Let rest 10 minutes before slicing and serving.