Preheat oven to 400ºF (204ºC). Generously spray a large baking sheet2 (or jelly roll pan) with non-stick spray. Set aside.
Break graham crackers into squares and arrange in the pan, covering the bottom but leaving a little bit of room between each square.
14 full graham cracker sheets
In a large saucepan over medium heat, bring butter and brown sugar to a boil. When mixture begins to boil, allow it to boil without stirring for 4-5 minutes. When mixture is bubbly and beginning to darken, pour it over the graham crackers.
1 cup (200g) lightly packed brown sugar, 1 cup (227g) unsalted butter
Immediately place baking sheet in the oven and bake for 8 minutes.
Remove toffee from the oven and pour the chocolate chips over the top, distributing them evenly. Allow to sit for a minute or two so the chocolate chips can melt.
2 cups (340g) semi-sweet chocolate chips
Using an offset spatula or a spoon, smooth the chocolate chips into one melted layer. Top with chopped nuts (or topping of your choice).
¼ cup chopped nuts1
Chill the toffee in the freezer for at least 1 hour OR in the refrigerator for 2 hours. Once the toffee is set, break into desired size pieces. Toffee can be stored in an airtight container in the refrigerator or at room temperature for up to 10 days. Toffee can be frozen up to 3 months. Thaw in refrigerator before enjoying.
Notes
Toppings: you may also use chopped candy and/or sprinkles.
Halve this recipe: cut everything in half and prepare in a casserole dish (approximately 7" x 12").
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.