Begin by combining the chocolate chips and butterscotch chips (if using) in a microwave-safe mixing bowl. Microwave in 30-second increments, stirring thoroughly between each, until the mixture is completely melted and smooth.
Incorporate the peanut butter into the warm chocolate mixture, stirring until the combination is fully integrated and silky.
Add the chow mein noodles and peanuts to the bowl. Gently toss the mixture until all the components are evenly coated in the chocolate-peanut butter blend.
Prepare a baking tray by lining it with parchment paper. Use a spoon to drop portions of the coated mixture onto the tray, shaping each into compact mounds resembling miniature haystacks.
Transfer the tray to the refrigerator and allow the haystacks to chill for approximately 30 to 45 minutes, or until set and firm to the touch.
Once hardened, serve immediately or store in an airtight container in the refrigerator for up to one week.