Preheat the oven to 350 degrees and lightly grease a loaf pan.
Place the ground beef and ground pork in a large bowl. Add the breadcrumbs, egg, onion, milk, salt, and black pepper.
Mix the ingredients with clean hands until they are evenly combined but not overworked.
Transfer the mixture to the prepared loaf pan and press it into an even shape.
Spread the ketchup evenly over the top of the meatloaf.
Bake for 60 minutes until the internal temperature reaches 160 degrees.
Remove from the oven and let the meatloaf rest for 10 minutes before slicing.