Preheat a griddle or a pan on the stove top to medium heat.
In a small bowl mix your butter, garlic and salt together. Set aside.
Lay out one slice of bread, top with a slice of Swiss cheese, then cheddar, then mozzarella and then top with another slice of bread.
Spread one side of sandwich with about 1/2 TBS of the garlic butter. Place onto your griddle, spread side down.
Coat top side with additional 1/2 TBS garlic butter.
Flip sandwich after a couple minutes and once bottom starts to turn golden brown.
Cook for additional 2 minutes until cheese is fully melted.
Repeat with additional sandwiches.