Sandwich assembly: Add any condiments you like to one side of two slices of bread. Add two to three slices of bread (or around 1/4 to 1/2 cup of shredded cheese) to one slice of bread, and then sandwich the cheese between the two slices of bread. 

Sandwich cooking: add a skillet or griddle to your stove and turn the heat way down to medium-low. If you have an electric griddle with a temperature gauge, shoot for 275 F (135 C). If you have an infrared thermometer, try to make sure the pan isn't getting much warmer than 300 F (148 C). 

Spread around 1 tablespoon of mayonnaise (or soft butter) on the exterior of one slice of bread. When the pan or griddle has preheated for a couple of minutes, add the sandwich, mayo/butter side down, in the pan. Cook for 4 to 5 minutes with the lid on top of the pan. If you do not have a lid, you can use an upside-down metal bowl or a sheet pan to form a cover over the pan. The trick is to allow the sandwich to steam while cooking so that the interior cheese starts to melt. 

After 4 to 5 minutes, spread another tablespoon of mayonnaise (or butter) onto the exterior of the top slice of bread and then flip the sandwich. 

Cook the sandwich for another 3 to 4 minutes and then continue cooking and flipping the sandwich every 1 minute until both sides of the sandwich are golden brown and crispy. 

Remove the sandwich from the pan and move it to a plate or a cooling rack.

Crispy cheese skirt: add 2 ounces of shredded cheese directly to the pan. Sprinkle the cheese in a shape that's just a bit larger than your sandwich. Place the sandwich down on top of the shredded cheese, right in the middle. 

Cook about 3 to 5 minutes or until the cheese starts to darken, has lost a lot of moisture, and is no longer really sticky when you poke at it with a spatula. 

Carefully scrape under the cheese to separate it from the pan. You might want to go all along the outside, scraping under the cheese for this process. Once the cheese starts to release smoothly from the pan, you can scrape all the way under with your spatula and remove the whole sandwich, cheese skirt and all, from the pan.

Allow the sandwich to cool, cheese skirt side up, for a couple of minutes on a cooling rack. If you do not have a cooling rack, you can use a rack from your oven or even something like two knives or chopsticks to keep the sandwich elevated off the surface. If your sandwich goes directly to a plate or cutting board, it will steam itself on the bottom and become soggy.