Preheat the oven to 250 degrees F.

Place the bread on an oven rack and toast until golden and well dried. Let cool.

Place a slice of cheese on top of each toast and cut into four squares.

Remove the cheese from the bread, slather a healthy dose of mayonnaise onto each square of toast, then top with a tomato slice, piece of bacon and square of cheese.

Return to the oven and cook for approximately 4 minutes more until the cheese bubbles. Serve immediately!