Preheat oven to 350 F.
Line a large baking sheet with a silicone mat or parchment paper. Cover with a single layer of Graham crackers.
Put butter, brown sugar, pecans and 1/4 teaspoon salt in a saucepan over medium heat. Bring to a boil and continue boiling for 2-3 minutes, stirring often.
Pour butter mixture over crackers. Bake for 15 minutes.
Melt chocolate per manufacturer's instructions in a microwave or in a double boiler. Pour over crackers, then sprinkle with more salt.
Refrigerate for 30 minutes, cut or break into bars, and serve.