Let the ice cream soften a bit. Work in half the butterscotch chips. When they are incorporated, swirl in some of the ice cream sauce and return the ice cream to the freezer to harden for at least 1 hour.
When you are ready to assemble: Take an individual trifle dish and put a cookie into the bottom, breaking it up into pieces to make it fit. Top with some sauce, then a scoop if ice cream, then some chips. Repeat until your dish is full, ending with the ice cream. Pour more sauce over the top, add some more chips, then the crushed candies.