01 -
Cover the outside of the bread slices with mayo, then add mustard to the inside of one. Stack up the cheeses on the side with mustard.
02 -
Pop the pan on low to medium heat. Melt enough butter to coat the surface.
03 -
With a lid on, let the sandwich cook for a couple minutes until the bottom looks golden.
04 -
Turn it over carefully, put the lid back on, and cook another minute or two until it’s golden and the inside gooey. Lower the heat if it's browning too quickly.