In a large microwave-safe bowl, combine the peanut butter, chocolate chips, and butterscotch chips. Microwave on high for 1 minute, stir, and continue microwaving in 30-second intervals, stirring after each, until the mixture is smooth and completely melted. Be careful not to overheat.

Add the chow mein noodles to the melted chocolate mixture. Gently stir until all the noodles are evenly coated. If using, stir in the chopped peanuts.

Using a spoon or a cookie scoop, drop clusters of the noodle mixture onto wax paper or parchment paper-lined baking sheets. Aim for bite-sized portions.

Allow the haystacks to set at room temperature for at least 30 minutes, or until firm. You can speed up the process by placing them in the refrigerator for about 10-15 minutes.