This recipe easily scales up and down. The amount of Parmesan butter and cheese-kimchi mixture needed will vary based on the size and quantity of your bread slices. Just keep the ratios the same and scale up or down as needed. For the butter, it's 1 part unsalted butter and 1 part Parmesan cheese. For the cheese-kimchi mixture, it's 1 part grated cheddar, 1 part grated Monterey Jack and 1 part chopped kimchi.