Empty crackers into plastic bag, add chopped onion, seal bag, take a tenderizing mallet and pulverize together. Pour into bowl with meat.
Chop onion the way you like, whether you prefer small pieces to bigger chunks. As for the green onion, I had the ends of a bunch left in the fridge, so I removed the roots, washed them off and chopped bulbs and scallion stalk as fine as I could to add to the mixture. Add onions.
Add remaining ingredients, milk according to how moist/dry the mixture is. Mix well either by hand or if you're the proud owner of a Kitchen Aid mixer, let it do the work.
Spray glass or metal baking pan with cooking spray, form into loaf depending on the pan, place in pan. In our house not everyone likes ketchup as a topping so we cover half the loaf with ketchup and half is left unscathed. Cover with lid or foil, shiny side down.
Bake for about an hour @ 375, 350 if a glass baking dish is used. With this I don't preheat the oven. I place the meatloaf in the oven and turn the oven on - everything acclimates together.
AS FOR THE OPTIONAL INGREDIENTS: whether you make this stovetop or oven, shredded cheese can be added to taste. Mom used to make meatloaf stovetop in a tomato soup sauce. When she did that she'd brown the loaf both sides and place it in the pot with the soup - ketchup wasn't used as topping . the meatloaf seasoned the soup nicely, but it did take a couple of hours to cook over low heat.
I imagine you could finagle baking it that way in an oven, and of course a crock pot would work, but in either case the loaf should be browned first.