Toast the bread (I recommend Rudi's for the gluten-free crowd - like my son - or Ezekiel), spread with all natural peanut butter (ingredients should say PEANUTS and that's all) and top with sliced banana. You can top yours with another piece of toast smeared with PB. I eat mine open-faced and find it's super filling and healthy!
This sandwich travels well for school or work lunches. Just pop in a plastic container free from toxic chemicals and go! Check the bottom of your container and be sure it's not stamped with #3 or #7. Bisphenol A (BPA) and phthalates are bad for you. Products labeled 1, 2, 4 and 5 are much safer. Run along and check your containers - and enjoy your PB & B sandwich!