Add butter, white sugar, corn syrup, salt and Herdez Red Guajillo sauce to heavy pan. Bring to a boil, stirring over medium heat. Once it comes to a boil, don't stir and bring the mixture to 290-300 degrees on a candy thermometer. Swirl the pan from time to time to avoid scorching.
Meanwhile, cover a cookie sheet with foil and spray with cooking spray. Spread toasted walnuts in even layer and set aside
When butter sugar mixture has reached 290-300 degrees, caerfully pour over walnuts. Then top this with dark chocolae chips. Let sit for a few minutes until chips melt and then spread in thin layer over toffee. Top with remaining walnuts. Chill to harden