Slice the bread into two evenly thick pieces of bread.
Slice and grate the cheeses before you begin heating the skillet.
Start heating the skillet over medium heat, (it's important to start with a hot skillet)
Spread 1 tablespoon of mayonnaise onto one side of each slice of bread.
Add half of the unsalted butter to the pan, let it melt, turn down the heat so it doesn't scorch.
Place both slices of bread in the pan with mayonnaise side facing up, and sprinkle the grated parmesan cheese evenly over the mayonnaise (1 Tablespoon per side)
Flip the bread slices over and arrange the other cheeses evenly across one slice of the bread.
Place the other slice of bread on top of the slice with the cheese. With the parmesan mayonnaise side up. Add the remaining unsalted butter to the pan.
After about 2 minutes on low heat flip the sandwich with the spatula being careful to keep both sides together.
Cook an additional 2 minutes or until all melted cheese is warm and gooey, remove the sandwich from the pan, cut in half if you want! And enjoy!
