Preheat the oven to 350 F
In a medium-sized bowl, mix the veggies with the beaten eggs, milk, and shredded Cheddar until well combined
Mix the ground beef, chopped parsley, salt, pepper, and breadcrumbs into the bowl until everything is well combined but not overmixed.
Put the meat mixture inside a loaf pan and bake for 30 minutes, uncovered.
While the meatloaf is baking, combine the ketchup, mustard, and brown sugar in a small bowl. Mix it until you feel most of the sugar has dissolved. Set it aside.
After 30 minutes, carefully take the meatloaf out of the oven and spread the ketchup mixture evenly over the top.
Continue baking the meatloaf, uncovered, for another 30 to 40 minutes. Let it sit for 15 minutes before cutting it.