Preheat the oven to 350 degrees.
In a medium bowl, mix together peanut butter, sugar and egg until crumbly dough forms.
Roll dough into one-inch balls with your hands and place in a mini muffin pan. Use thumb to press small indention into each cookie.
Bake for 12 minutes
In a medium bowl mix the butter, vanilla and green food coloring.
Add powdered sugar a half cup at a time and mix until combined.
Add milk and mix until creamy.
To create the Easter nests, place frosting in a piping bag or a plastic baggie with the tip snipped off. Pipe frosting onto each cookie and top with chocolate egg candies.