Preheat oven to 350 degrees.

Line a cookie sheet with foil and lightly grease.

Place graham crackers on the cookie sheet in one layer.

Sprinkle pecans evenly over the graham squares.

In a small sauce pan melt the unsalted butter.

Add brown sugar to the pan and stir until mixture begins to boil.

Pour sugar mixture over pecans and graham squares.

Bake in oven for 10 minutes.

Remove pan from oven and place into freezer for 1 hour.

Break bark into pieces while still cold.