Approximately 14 graham crackers (if each graham cracker is 5" x 2.5")
1 cup (2 sticks) unsalted butter
1 cup packed dark brown sugar
1 cup chopped pecans
Kosher salt, to taste
12 ounces dark chocolate, finely chopped *Use good quality chocolate, very important
1. Preheat the oven to 350 degrees F.
2. Line a rimmed baking sheet with a silicone mat or spray with nonstick cooking spray. Arrange the graham crackers in a single layer on the lined baking sheet.
3. Put the butter, brown sugar, pecans, and a pinch of salt in a saucepan and bring to a boil. Boil for 2 to 3 minutes, stirring constantly. Pour the butter mixture evenly over the graham crackers and bake for 15 minutes. Remove and set aside.
4. Meanwhile, melt the chocolate in a glass bowl placed over simmering water. Pour the chocolate over the toffee-covered graham crackers and spread evenly. (If desired, sprinkle flaky sea salt over the dark chocolate layer.) Chill completely in the refrigerator for about 30 minutes. Cut into bars.