01 -
Spread a thin, even layer of mayonnaise on one side of each bread slice. Place the slices mayo-side down on a board.
02 -
Spread 1 tablespoon peanut butter on the dry side of each bread slice, reaching close to the edges.
03 -
Arrange the banana slices over two of the peanut-buttered slices in a single layer. Sprinkle lightly with cinnamon if using.
04 -
Top with the remaining bread slices, peanut butter side down, so the mayonnaise is on the outside of each sandwich.
05 -
Heat a nonstick skillet or griddle over medium heat. Cook the sandwiches for 2-3 minutes per side until the bread is crisp and golden and the filling is warm.
06 -
Let the sandwiches rest for 1 minute, then slice. Finish with a tiny pinch of flaky salt if desired and serve warm.