Step 1

Preheat oven to 400 F.

Step 2

Grate the onion using the large holes on a box grater. Add to a medium-large mixing bowl. Add the oatmeal, whole milk, garlic powder, horseradish, ¼ cup ketchup, 1 teaspoon yellow mustard, and salt to the onion. Mix well with a fork. Let it sit for 5 min.

Step 3

While that's resting, combine the remaining ½ cup ketchup, 1 teaspoon yellow mustard, and brown sugar well with a fork in a separate bowl.

Step 4

Line a large rimmed baking sheet with aluminum foil and spray with nonstick cooking spray.

Step 5

Add the beef to the onion and oat mixture and combine with your hands. Form 6 small mini-meatloaves on the prepared baking sheet, about 1 ½ inches thick and 4x6-inches. Brush with the ketchup, mustard, and brown sugar glaze.

Step 6

Bake at 400 F for 25 min. Check the internal temperature with a probe thermometer to ensure it is cooked to 155 F.

Step 7

Let rest for 5 min and then enjoy!