Preheat your oven to 400°F (200°C). Line a sheet pan with aluminum foil if desired for easier cleanup.
In a mixing bowl, combine the ground beef, breadcrumbs, milk, egg, ketchup, Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Mix until just combined, but do not overmix. Form the mixture into 8 small meatloaves and set aside.
In another bowl, toss the halved baby potatoes with olive oil, dried rosemary, garlic powder, salt, and black pepper until evenly coated.
Spread the seasoned potatoes across one side of the sheet pan, leaving space for the mini meatloaves.
Place the mini meatloaves on the other side of the sheet pan.
Bake in the preheated oven for 25-30 minutes, or until the meatloaf is cooked through (internal temperature should reach 160°F/70°C) and the potatoes are golden and tender.
Remove the sheet pan from the oven and let cool for a few minutes before serving.