Cook the Beef
Heat a skillet over medium-high heat. Add ground beef and onion. Cook until beef is browned and onion is soft. Season with salt, pepper, garlic powder, and paprika. Drain excess fat.
Prepare the Bread
Butter one side of each bread slice evenly.
Assemble the Melt
Place one slice of bread butter-side down in a skillet. Add a generous layer of beef, followed by cheese. Top with another slice of bread, butter-side up.
Grill
Cook over medium heat until the bread is golden and the cheese starts to melt. Flip carefully and cook until the second side is crisp and the cheese is fully melted.
Serve
Remove from heat, rest for 1–2 minutes, slice, and serve hot.