Begin by heating a skillet over medium-high heat and cook the ground beef until it is fully browned, which should take about 7–9 minutes. Drain any excess fat.
Next, reduce the heat to medium and season the cooked beef with salt, pepper, garlic powder, and onion powder. Stir the mixture to combine and cook for an additional minute.
While the beef is cooking, spread butter on one side of each slice of bread.
On a clean surface, place one slice of bread with the buttered side facing down. Layer the slice with cheddar cheese, followed by the cooked beef, and then top with mozzarella cheese. Place the second slice of bread on top, buttered side facing up.
Heat a clean skillet over medium heat and toast the sandwich for 3–4 minutes on each side, pressing lightly until it turns golden brown and the cheese is melted.
Once done, remove the sandwich from heat, let it rest for a minute, then slice and serve warm.