COOK bacon until it is well-done and crispy. Set aside to rest.
SPREAD mayonnaise on the outside of each piece of bread.
LAYER Swiss, bacon, tomato and shredded lettuce onto bread.
TOP with final slice of bread.
HEAT a pan on medium-low heat.
PLACE your sandwich into the pan.
FLIP the sandwich when bread starts to turn golden brown and cheese has begun to melt.
REMOVE from the pan once both sides of your bread are toasted and the cheese is fully melted.