Lay a piece of wax or parchment paper on your counter top.
In a double boiler, melt the butterscotch, butter, and peanut butter. Stir frequently.
Once everything is melted and smooth, add in the shortening to thin out the butterscotch mixture. Stir the shortening through.
Remove from the heat and add in the chow mein noodles. Stir until all the noodles are covered. There should be just enough butterscotch mixture to cover the noodles.
After you've covered all the noodles, lay them out on the parchment paper. You don't want the noodles overlapping too much. Let dry for 20-30 minutes.