1. Preheat oven to 375 degrees Fahrenheit. Line a 15-inch x 10-inch x 2-inch pan with foil, leaving a 2-inch overhang at each end.
2. Line pan end-to-end with graham crackers.
3. Melt butter or margarine in a saucepan on medium to low heat. Add sugar and salt and cook until smooth and blended, about one minute.
4. Pour over crackers, spreading evenly. Bake on the middle rack of the oven until golden brown and bubbling, about 10 minutes.
5. Scatter chocolate chips evenly over crackers and return to oven for about two minutes. Wait until chocolate chips are fully melted.
6. Remove from oven and spread melted chocolate with an offset spatula. Sprinkle with chopped walnuts, almonds or raisins.
7. When fully cooled, break into bite-size pieces.