Heat a medium nonstick pan on medium-low. Place bread on a work surface and spread each slice with peanut butter, dividing evenly. On 1 slice, layer banana and cheese. Top with remaining slice of bread, peanut-butter side down. Place sandwich in pan and cook, turning once, until bread lightly toasts and cheese melts, about 2 minutes per side.
This Mexican-inspired fondue is simple yet flavorful, and it cooks right on the grill – though you can also use the stove top or your grill’s side burner, if it has one. For dipping, serve chunked grilled or raw vegetables, chunked grilled sausages and tortilla chips on the side.