Place marshmallows, peanut butter, and butter in a saucepan; cook and stir over medium heat until the marshmallows have melted completely, about 5 minutes.

Put chow mein noodles into a large bowl; pour marshmallow mixture over noodles and stir to coat.

Spray hands with cooking spray or coat with butter so the noodles will not stick to your hands. Scoop noodle mixture from bowl with an ice cream scoop and form into balls, hollowing the center out to create the nest. Arrange 4 chocolate eggs into each nest.