Tangy cheese inside, crispy cheese on the outside… This is cheesy perfection.
Grated cheddar cheese
Spread the mayo very thinly on one side of the sliced bread slices.
Melt butter in a pan and place one slice, mayo side down, in the butter. Grill until slightly crispy, remove from pan.
Add a little more butter and add the other slice to the pan, also mayo side down. Put the grated cheese on the slice, some black pepper and dots of the optional mustard. Place the other slightly grilled slice on top. Add grated cheese on the top slice and flip the sandwich. Add grated the cheese on the other side and flip again after the cheese is nice and crispy, about a minute. Both outsides should have a touch of brown, and crispy.
Serve and enjoy.