Preheat the oven to 350°F.
Heat the olive oil in a small pan. Add the diced onion and bell pepper and cook for about 5 minutes, until they are soft. This helps create a smooth texture and mild flavor. Set aside and let them cool.
In a large bowl, add the beaten eggs, crushed Ritz crackers, cooked onions, bell peppers, shredded cheese, milk, salt, and pepper. Stir until everything is well mixed.
Add the ground beef and gently mix until just combined. Do not mix too much, as this helps keep the meatloaf tender.
Shape the mixture into a loaf and place it into a loaf pan. Using a loaf pan helps the meat hold its shape and cook evenly.
Bake for 30 minutes.
While it is baking, mix the ketchup, brown sugar, and mustard in a small bowl and set aside.
After 30 minutes, remove the meatloaf and spread the topping over the top. Return it to the oven and bake for another 30 to 40 minutes. Remove it when the inside reaches 155°F.
Let the meatloaf rest in the pan for 15 minutes before slicing. During this time, the temperature will rise and the juices will stay inside. Make sure the center reaches 160°F before serving.
Serve with creamy mashed potatoes.