In a bowl, combine 2 tbsp butter, 1 tbsp minced garlic, 1/2 tbsp sugar, and 1/2 tbsp parsley flakes. Microwave for 15 seconds to melt the butter.

Spread the melted garlic butter sauce on one side of each bread slice.

Place the bread slices buttered-side down. Add 2 slices of cheddar cheese and a generous amount of mozzarella cheese on top.

Top with the remaining bread slice, then cook on low heat until the bottom side is golden. Flip carefully and cook the other side.