Pre-heat the oven to 375 degrees.
Line a 13- x 10-inch rimmed cookie sheet (with low sides) with aluminum foil, leaving a slight overhang.
Arrange the graham crackers in a single layer on the prepared cookie sheet, breaking the cracker to fit if necessary; set aside.
In a heavy saucepan over low heat, melt the butter and brown sugar. Cook approximately 5 minutes, stirring frequently, until smooth. Remove from heat.
Pour the hot butter mixture over the top of the graham crackers, spreading evenly and completely covering the top of the crackers. Place in the oven and bake for approximately 10 minutes. Remove from heat.
Scatter the chocolate chips evenly over the top of the crackers. Return to the oven and bake approximately 2 to 3 minutes or until the chocolate softens.
Remove from oven and, using a spatula, spread the melted chocolate chips evenly over the crackers. Sprinkle the chopped nuts evenly over the top of the chocolate.
Let cool until harden. For a quick hardening, cool for 30 minutes and then transfer the baking sheet with the toffee to the freezer for 15 minutes.
When cool, break or cut toffee into pieces.
* If using unsalted butter, add 1/8 teaspoon salt.
** Use a good-quality chocolate chips for best flavor.
Graham Cracker Toffee Recipe: https://whatscookingamerica.net/candy/grahamcrackertoffee.htm