Put the ground meat, eggs, chopped onions, bread crumbs/oats, Worcestershire sauce and 1/2 cup of the ketchup into a large bowl.
Mix all ingredients together (Some people try to do this with a large paddle spoon, but I just smash everything together using one hand, keeping the other hand clean so I can add more bread crumbs or oats, if necessary - the mixture should be firm, so it will stick together while baking, but not stiff.
While the mixture is still in the bowl, begin shaping it into one or two oblong "loaves."
Put the loaf or loaves into the prepared baking pan.
Top the loaf/loaves with the rest of the ketchup.
Bake at 350 degrees F for about 75 minutes.
Remove from oven and immediately take your meatloaf out of the pan and place on plate.
Allow the meatloaf to cool for five minutes before slicing.