Preheat oven to 400. Line a cookie sheet with sides with foil and spray with cooking spray. Place crackers on pan.
In saucepan combine brown sugar and butter. Bring to boil. Boil for 5 min, stirring constantly. Pour over crackers. Put in oven for 4-1/2 min.
Remove from oven and sprinkle with chocolate chips. Put back in oven for 1 min. Remove from oven and spread melted chips evenly. Dust with chopped nuts. Cool and refrigerate at least 2 hours. Break in pieces for serving.