Preheat the oven to 350°F, line a rimmed 11x17 inch sheet pan with foil and parchment, then arrange a single layer of graham crackers edge to edge covering the pan.

Melt 1 cup butter with 1 cup packed brown sugar in a saucepan over medium heat, stirring until it comes to a full boil.

Boil the butter-sugar mixture for exactly 3 minutes without stirring, until it turns a shade darker and coats the spoon in a glossy caramel layer.

Pour the hot caramel evenly over the crackers and spread quickly with an offset spatula before it sets.

Scatter 1.5 cups chopped pecans evenly over the caramel.

Bake for 8 to 10 minutes, until the caramel is bubbling all over, not just at the edges.

Remove from the oven and let cool on the pan for 10 minutes, then drizzle the melted chocolate over the top in thin lines.

Sprinkle with flaky salt and let cool completely, about 1 hour, until the chocolate is fully set and snaps when pressed.

Break into irregular shards by hand.

Weigh into 6-ounce portions and seal each portion in a small clear cellophane or resealable bag.