When I was a kid we hardly ever had meatloaf. The story was that when my parents were first married they didn't have much money and ground beef was very cheap so they ate a lot of it. My father, when he started to make more money, didn't want to see meatloaf on his table again (likewise....we never had steak cooked on the grill....steak was too expensive to risk the possiblility of burning on an open fire.)! But...I like meatloaf and so do my daughters and so does my husband. And...with just some minor tweaking, it's a low carb favorite.
First I take a one pound package of ground beef (grass fed...of course!) and a one pound package of ground pork. 
Those get dumped together in a bowl along with one small diced onion (to lower the sugar carbs I often use scallions...then you need two or three), one stalk of diced celery, two tablespoons of ketchup, one tablespoon of mustard, and 1/4 to 1/2 cup of Panko crumbs (NOT white bread crumbs).

Sprinkle on some salt and pepper to taste and mix it all together. With you hands. I find that if I rinse my hands under the water and don't dry them, the water on my hands provides enough moisture. When everything is well mixed,

form the blob into a loaf about 2 inches high and 4 inches wide.

I put my raw meatloaf into a small baking pan....not a loaf pan. I like the fat to drain away from the meat. Then put the loaf into a 350 degree F oven for about an hour.
For pizza meatloaf you'll need to have some cheese ready to top the loaf and you'll need to make a tomato sauce. I like to make a fresh tomato sauce. Easy and less chance of chemicals or HFCS! The recipe for my fresh tomato sauce is on this web site.
When your meatloaf is done, put the chees of your choice on top and push it back into the oven for only a few minutes for the cheese to melt. When the cheese has melted, using a large spatula, remove the loaf from the pan and place it on your serving platter.

You can ladle some tomato sauce over it before serving, or you can serve it with a bowl of the sauce on the side.

I serve the sauce on the side because everyone has a different idea of how much sauce is just the right amout. Papa Bear says too little! Baby Bear says too much! So Mama Bear fixes it just right!