Place the bacon in a large skillet over medium heat. Cook until crisp. Place the bacon on a paper towel lined plate to drain (keep the bacon grease in the pan), then chop into fine pieces.
Add the onion to the bacon grease. Cook until soft, about 3–4 minutes. Remove the onions but leave the bacon grease (which you can save for another use or discard).
In a large bowl, combine the ground pork, ground round, breadcrumbs, eggs, worcestershire sauce, parsley, cubed cheddar, salt, chopped bacon, and cooked onions. Mix very gently with your hands to combine.
Pour the mixture onto a baking sheet with a rimmed edge. Form it into a loaf with your hands, packing it gently so it stays together.
Place in the oven and cook for 45 minutes.
Meanwhile, combine the ketchup and ranch dressing in a small bowl. Remove the meatloaf from the oven and pour the ketchup mixture on top. Return to the oven for 8–10 more minutes, or until the meat reaches an internal temperature of 160°F.
Remove from the oven and let rest for 5 minutes before slicing.