Line a 9x9-inch square baking pan with aluminum foil and lightly spray with nonstick spray.
Place crackers in single layer of pan to cover the whole bottom. Break the crackers as necessary to fit.
Spread brown sugar on the bottom of a small saucepan. Cut butter into about 8 slices and place on top of sugar. Place pan on top of medium-high heat and without stirring bring to a boil. Let boil about 2-4 minutes or until smooth and brown in color.
Pour toffee mixture (sugar and butter) over graham crackers and spread evenly with an offset spatula. Bake for about 5 minutes at 425 degrees F to set.
Sprinkle peanut butter chips evenly over crackers and place back in oven for about 2 minutes or until chips start to melt. Remove from oven and spread chips evenly over crackers.
Sprinkle chopped nuts on top and gently press into the smooth peanut butter chips. Sprinkle chocolate chips evenly over nuts and place back in oven for about 2 minutes or until chocolate chips start to melt. Spread chocolate evenly over nuts. Cool.
Place in refrigerator for about an hour or until chocolate sets. Break or cut into pieces.
SNAPPY TIPS: If bars aren't completely cool before placing in the refrigerator place on a trivet. To expedite cooling you could also place bars in freezer.SNAPPY SUBSTITUTIONS: I have only used real unsalted butter in this recipe. Substituting margarine or anything else may have different results. Instead of semi sweet chocolate chips you could use dark chocolate.