Preheat the oven to 375 degrees and line a baking sheet with parchment paper.
In a large bowl, combine the ground beef, gochujang, panko breadcrumbs, egg, onion, garlic, soy sauce, and sesame oil. Mix until the ingredients are evenly distributed.
Divide the mixture into four equal portions. Flatten each portion slightly, place one cheddar cube in the center, and shape the meat around the cheese to fully enclose it.
Place the formed meatloaves on the prepared baking sheet and bake for 25 minutes, or until the internal temperature reaches 160 degrees.
Remove from the oven and let rest for 5 minutes. Sprinkle with sliced green onions and sesame seeds before serving.