Yep saltines. I was a little skeptical at first when I found this recipe but I gave it a try and it was so easy and very tasty. It doesn't have the consistency of fudge made with marshmallow but it is still good. Hope you give it a try.
Place the sugar, butter and milk in a saucepan and heat on medium until it starts to boil. Stir occassionally. Once it starts to boil, boil for 1 minute only and remove from heat. Be very careful as the liquid will be extremely hot. If it is lukewarm you didn't bring it to a boil.
Stir in peanut butter, saltines and vanilla. Mix well. Pour into a greased 8 x 8 pan and chill. Cut into bite size pieces.
Note: To crush the saltines just stick them in a plastic storage bag and roll a rolling pin over them. The key word here is crushed. You want them fine not in junks.
Additional Note: you can add choc. chips during the second stage also. Others have tried this recipe using different butters as in almond butter and nutella. Have fun with it. It is a very versatile recipe.