In a large bowl, using your hands or a spoon, gently mix ground beef, onion, eggs, breadcrumbs, garlic, milk, italian seasoning, parsley, salt, pepper, and ketchup. Do not overmix or it will create a tough loaf.
Shape this mixture into a round loaf. Place it on a large piece of tin foil. Create a loaf pan around the loaf by crimping the edges of the foil around the meatloaf. It should be about the size of the instant pot trivet.
Put the trivet into the instant pot. Make sure the handles are pointed up to make the loaf easier to remove later. Place ½ cup of water into the instant pot, then put the meatloaf onto the trivet. Lock the lid into place. Pressure cook on high power for 40 minutes. When cooking time is over, you may use the quick release.
While the pressure is releasing, make the glaze. In a small bowl, whisk together ketchup, brown sugar, and worcestershire sauce.
Remove the meatloaf from the instant pot. Drain any excess grease.
Place it on a baking sheet and spread the glaze all over it. (If there is extra glaze, save it for later.)
Broil the meatloaf for 5-7 minutes, or until the glaze is bubbly.