In a large bowl, combine ground beef, bread crumbs, onion, milk, eggs, ketchup, Worcestershire sauce, garlic powder, salt, and black pepper. Mix gently.

Loosely pack the meatloaf mixture into wide-mouth pint jars, leaving 1 inch of headspace. Optionally, add a spoonful of ketchup on top.

Wipe jar rims, place lids, and screw on bands fingertip-tight.

Pressure can jars according to your canner’s instructions, typically 75–90 minutes for pints.

Allow pressure to drop naturally, remove jars, cool on a towel, check seals, and store in a cool, dark place.