Put two pieces of bread on the counter. Spread half the peanut (or almond) butter on each slice.
Top each slice with half the banana slices. Cover each with another slice of bread.
Put a skillet on the stove and turn the heat to medium.
After about 2 minutes, add the sandwiches.
After about 2-3 minutes, the bottom should be golden brown. Using a spatula, flip each sandwich and cook until the new bottom is golden brown, 2-3 minutes.
Using a spatula, put the sandwiches on a plate, let cool for a few minutes and cut in half.