Preheat your oven to 375°F (190°C). Cover a baking sheet with parchment paper.
Place the lean ground beef in a large skillet over medium heat. Cook until browned and fully cooked, breaking it apart as it cooks. Drain any excess fat.
Stir the ketchup, yellow mustard, and onion powder into the cooked beef. Continue cooking for about 2 minutes, stirring occasionally, until the mixture is well combined and slightly thickened.
Arrange the hot dog buns next to each other on the prepared baking sheet. Carefully make an opening in each bun without cutting completely through it.
Divide the warm beef mixture evenly among the 8 buns, spooning it neatly into the center of each one.
Sprinkle the shredded cheddar cheese evenly over the beef filling.
Place the baking sheet in the oven and bake for 10–12 minutes, or until the buns are lightly toasted and the cheddar cheese has melted completely.
Remove from the oven and serve the cheesy beef hot dog buns while they are warm.
