Start by toasting the bread slices in a toaster or on a skillet over medium heat until golden brown, about 3-4 minutes.
STEP 2
While the bread is toasting, slice the avocado in half, remove the pit, and scoop the flesh into a bowl. Mash it with a fork and season with salt and pepper to taste.
STEP 3
Once the bread is toasted, spread a generous layer of the mashed avocado on one slice.
STEP 4
Place slices of cheese on top of the avocado. If using a cheese that melts well, you can place the sandwich in a skillet over low heat to melt the cheese for about 2-3 minutes.
STEP 5
Top with the second slice of bread and serve immediately.