Preheat the Oven: Set the oven to 350°F (175°C). Line a rimmed sheet pan — a half-sheet pan works well — with aluminum foil. The foil ensures easy cleanup and prevents sticking. Lightly grease the foil with butter or nonstick spray to keep the bark from clinging once baked.
Arrange the Base: Lay the graham crackers in a single, even layer across the prepared baking sheet. Break crackers as needed to fit snugly and cover the entire surface. The crackers form a crisp, slightly honeyed base that complements the pecan topping beautifully.
Make the Pecan Topping: In a medium saucepan, combine the butter, brown sugar, chopped pecans, and salt. Place over medium heat and stir gently as the butter melts and the sugar dissolves. Bring the mixture to a low boil and continue cooking for 2 minutes, stirring constantly to prevent scorching. The mixture should become glossy, fragrant, and slightly thickened — a sign that the sugar is caramelizing properly.
Add Vanilla and Pour: Remove the pan from heat and immediately stir in the vanilla extract. Be careful — the mixture will bubble slightly when the vanilla hits the hot caramel. Quickly pour the hot topping over the graham crackers. Using a spatula or the back of a spoon, spread it evenly to the edges of the pan, ensuring all the crackers are coated and the pecans are evenly distributed.
Bake: Place the baking sheet in the oven and bake for about 10 minutes, or until the topping is bubbling across the surface. This step helps the caramel seep into the graham crackers, giving the bark its signature crunch once cooled.
Cool and Break: Remove the pan from the oven and set it on a heat-safe surface to cool completely. The topping will be hot and soft at first but will firm up as it cools. Once cooled and hardened, lift the foil from the pan and gently break the bark into irregular pieces.
