Spread peanut butter on as many saltine crackers (or Ritz) as you like (I love the Zesta wheat crackers). Top each with a marshmallow.
Note: Use one regular marshmallow or 4 to 6 miniature marshmallows or a whopping teaspoon of marshmallow creme. I've used all of them at some point. I wouldn't recommend the super large marshmallows though.