Preheat oven to 350 degrees. Coat a regular size (12-cup) muffin tin with cooking spray.
To make bread crumbs: remove crust, break up the bread, and add to a blender or food processor. Process until the bread turns into crumbs.
In a large bowl, add the ground beef, bread crumbs, onions, egg whites, ketchup, mustard, Worcestershire sauce, salt, and pepper. Using your hands, mix together until well.
Using a ⅓ cup measuring cup, fill 9 muffin cups. In a small bowl, mix together the topping ingredients. Spread about 2½ teaspoons topping all over the top of each meatloaf cupcake. Bake for 40 minutes.
While the meatloaf is baking, make the mashed potatoes. Add potatoes to a pot and cover with water. Bring to a boil, cover, and simmer for about 15-20 minutes until tender. Drain potatoes into a colander and place drained potatoes back in the pot. Mash potatoes with a fork. Add the butter or Smart Balance, broth, and a little salt and pepper. Turn flame to medium and continue to mash potatoes until smooth and all the ingredients are heated.
Remove meatloaf muffins from pan and place on paper towels to drain the fat. Top each with 2 rounded tablespoons of mashed potatoes and serve.