Cook the bacon in a skillet over medium heat until crisp. Remove the bacon, drain on paper towels, and crumble it into small pieces. Leave about 1 tablespoon of bacon fat in the skillet.

Add the diced onion to the same skillet and cook for 5 minutes until soft and lightly golden. Let the onion cool slightly.

Heat the oven to 375 degrees and line a baking sheet with parchment paper.

In a large bowl, combine the ground beef, crumbled bacon, cooked onion, breadcrumbs, egg, milk, smoked paprika, salt, and black pepper. Mix with your hands until just blended.

Divide the mixture into 4 equal portions and shape each into a small loaf about 3 inches long. Place them on the prepared baking sheet.

Stir together the ketchup, brown sugar, and mustard in a small bowl. Spread the glaze evenly over the top and sides of each mini meatloaf.

Bake for 25 minutes until the internal temperature reaches 160 degrees. Let the meatloafs rest for 5 minutes before serving.