In a large bowl, add ground beef, egg, sour cream, bread crumbs, Worcestershire sauce, ketchup, salt, pepper, parsley, garlic powder, Montreal seasoning, dried onion flakes and Parmesan. Using your hands or a wooden spoon, mix ingredients together being careful not to over mix.
Using a ⅓ cup measuring cup, scoop out meatloaf mixture and place into one cup of muffin pan. Continue fulling cups until all meatloaf mixture is used. Spoon 1 teaspoon of ketchup on top of each meatloaf. Place in oven and cook for approximately 25 minutes until meatloaf muffins are brown and pulling away from side of pan.
Remove from oven and serve immediately. ***Meatloaves can be frozen. Cool and place in a freezer safe container or zip top back and freeze for up to 3 months. To serve, thaw and reheat meatloaf muffins until warmed through.