Preheat oven to 350 degrees F. Line a large rimmed baking sheet with parchment paper or aluminum foil sprayed with nonstick spray.

In a large bowl, combine the ground beef, ground pork, chopped onion, tomato paste, eggs, milk, panko bread crumbs, Worcestershire sauce, minced garlic, thyme, salt, pepper, and parsley. Do not add the cream cheese or ketchup at this stage.

Cut both packages of cream cheese into large chunks with a knife and set aside on a plate.

Use your hands to mix the meat mixture until just combined. Stop as soon as there are no dry spots. Do not overmix.

Turn the meat mixture out onto the prepared baking sheet and pat it into a large, even rectangle roughly 10 by 14 inches.

Arrange the cream cheese chunks in a single row down the center of the rectangle lengthwise. Leave at least a 2-inch border of meat on all sides.

Carefully fold one long side of the meat up and over the cream cheese, then fold the other long side on top. Press the edges firmly together to seal all the way around. Pinch and smooth any gaps you find.

Spread ketchup evenly over the entire surface of the loaf.

Bake at 350 degrees F for 40 to 50 minutes, or until a meat thermometer inserted into the thickest part reads 160 degrees F. Do not rely on time alone as oven temperatures vary.

Remove from the oven and let the meatloaf rest for 5 to 10 minutes before slicing and serving.