Arrange crackers in a single layer on the bottom of a 10x15 inch pan that has sides.
Boil the butter and the brown sugar together for 3 minutes. Pour evenly over the crackers. Be careful it's extremely hot and sticky.
Bake at 375 degrees F (190 degrees C) for 7 minutes.
Remove from oven and immediately sprinkle chocolate chips over hot mixture. Wait a few minutes for them to melt, then spread evenly with the back of a spoon. While still hot spread finely chopped walnuts over the top. Break or cut into desired size pieces.
