Preheat the oven to 375 degrees. Lightly spray the muffin pan with nonstick spray, and set aside.
In a large mixing bowl, combine the ground beef, onion, bread crumbs, tomato sauce, eggs, worcestershire sauce, minced garlic, dried parsley flakes, kosher salt, black pepper and ground mustard seed.
Using either a large wooden spoon, or gloved hands (I usually choose this option), mix together all the ingredients until they are completely incorporated.
Spoon the ground beef mixture into a standard size muffin pan. Completely fill each muffin cup to the top line of the cup. (I used a 3-tablespoon cookie scoop).
Using a teaspoon, top each muffin with ketchup for the glaze.
Bake for 30 minutes.
Any leftovers can be kept in an airtight container in the refrigerator.
You can frost these meatloaf muffins with your favorite mashed potato recipe.
You can use either a decorator’s icing piping bag and a large #8 icing tip. Or, if you do not have either the piping bag or the large tip, you can use a quart (or gallon) size ziplock bag.
How to "Frost" Mini Meatloaf Muffins
If using the piping bag and tip, place the coupler and tip into the bag.
Fill the piping bag half full. Be sure to twist the bag above the potatoes to help keep even pressure and ensure no air pockets in the piping bag.
Starting on the outside edge and following around toward the center, hold the tip just above the muffin and evenly squeeze out the potato frosting in a swirl pattern. Allow the “frosting” to spread out just a bit as you go, until you reach the center.
If you are using a Ziploc bag, fill the bag ½ full. Zip the baggie closed, making sure to remove any extra air.
Using scissors, snip off a small corner tip of the ziploc. The size of the snip depends on how large you want your “frosting” to be.
Follow the same directions as described if you were using a piping bag.
You can also sprinkle minced chives on top of your potato frosting.