Line a baking sheet with foil and preheat the oven to 350°F.
Use butter to grease the foil on the baking sheet then arrange the graham crackers on there, breaking some if necessary so they fit in a single layer.
Bring the butter, pecans, sugar, and salt to a boil in a pan.
Cook for 2 minutes, stirring all the time.
Take the mixture off the heat, then mix in the vanilla.
Pour it over the graham crackers on the baking sheet, spreading it to the edges.
Ensure all the crackers are covered and the nuts are more or less evenly distributed.
Bake for 10 minutes or until bubbling.
Cool then break into pieces and serve.