Line a large baking sheet with parchment paper or a silicone baking mat. Set aside.
Add the chow mein noodles to a large bowl. Set aside.
In a small microwave-safe bowl or a glass measuring cup with a spout, combine the butterscotch chips and peanut butter. Heat in the microwave in 30 seconds increments on MEDIUM heat, stirring after each increment, until mixture is smooth. Take care not to scorch the butterscotch chips by utilizing the stirring more than you think you need to (distributing the heat will help the chips melt).
Pour the butterscotch and peanut butter mixture over the chow mein noodles, then stir with a large spatula until everything is coated. Use the spatula to crush the noodles as you stir, breaking them into smaller pieces but not totally mashing them.
Use a cookie scoop to portion out mounds of the coated chow mein noodles onto the prepared baking sheet. You can use any kind of scoop size you like, but I used this #50 cookie scoop, which is what I use for all of my cookies. Press the mounds together a bit (they will land a little haphazardly on the baking sheet after scooping). Allow the haystack cookies to set on the baking sheet until coating is firm, about 2-3 hours. Store leftovers covered tightly at room temperature up to 1 week.
Notes
Peanut butter: do not use natural peanut butter. You can also use crunchy peanut butter if you want salty peanuts in the mix.
Nutrition Disclosure
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.