Preheat oven to 350 degrees F.
Line a large sided baking tray with parchment paper. Arrange the graham crackers in the center of the tray on the parchment.
Sprinkle the pecans over the crackers. Set aside.
Add the unsalted butter, fine sea salt and brown sugar to a small saucepan.
Melt the butter and sugar over medium heat. Whisk smooth. Bring the mixture to a boil and continue stirring for about 2 minutes.
Pour the hot sugar mixture over the crackers and pecans. Use a spatula to spread the mixture evenly over the crackers.
Bake in preheated oven for 10 minutes.
Remove from oven. Cool completely at room temperature. Break up the crackers and add to food processor bowl. Pulse until crumbs. Add melted butter to food processor. Pulse until crackers have been processed into crumbs.
Line the bottom and two opposite sides of a 9-inch square pan with parchment paper, leaving enough parchment on the two opposite ends to create handles for lifting the cheesecake bars out of the pan. Press the crumbs into the bottom of the pan. Use a flat bottomed glass or small offset spatula to create an even crust.
Refrigerate until ready to use.