In a medium saucepan over low heat, melt the chocolate chips and peanut butter together, stirring constantly until smooth and well combined. Remove from heat and stir in the vanilla extract and a pinch of salt.
In a large mixing bowl, combine the chow mein noodles and mini marshmallows. Pour the melted chocolate-peanut butter mixture over the noodles and marshmallows, and gently fold until everything is evenly coated.
Using a spoon or your hands, drop spoonfuls of the mixture onto a baking sheet lined with parchment paper. Shape them into small haystack mounds.
Refrigerate the haystacks for at least 30 minutes to allow them to set.
Once set, serve immediately or store in an airtight container in the refrigerator for up to one week.