Preheat oven to 350°F.
Add olive oil to a skillet and place it over medium-high heat. Add the onion and bell pepper. Cook, stirring occasionally, for 5-6 minutes, until the veggies are soft.
Add the garlic to the skillet. Cook, for one minute, stirring often. Remove the skillet from the heat.
In a large mixing bowl, add the egg. Scramble it with a fork.
Add the ground beef, breadcrumbs, milk, ketchup, Worcestershire sauce, salt, dried parsley, and pepper to the bowl.
Once the sautéed veggies are cool enough to touch, add them to the meatloaf mixture.
Use your hands to mix and mash the meatloaf mixture together until it is well combined.
Add the cubed cheese to the meatloaf. Mix until well incorporated.
Transfer the meat mixture to a 9x13" baking dish. Press and pat the meat into an even loaf form.
Top the meatloaf with the ketchup. Spread it out evenly over the top and sides.
Bake for 55 minutes.
Let the meatloaf cool for 10 minutes before slicing into 10 equal pieces.