Preheat oven to 350ºF.

Place chocolate chips in a medium mixing bowl.  Microwave in 30-second intervals, stirring often, until chips are completely melted and smooth.  Set aside.

In another medium bowl, whisk eggs and vanilla together.  Set aside.

In a separate large mixing bowl, cream butter and sugars together with a hand mixer.

While continuing to mix, slowly add egg mixture.  Beat until smooth.

Next, slowly pour in melted chocolate chips while continuing to beat.

Add flour, cocoa powder, baking powder, and salt.  Beat again until uniform dough forms.

Using a cookie dough scoop, place scoops of dough on a baking sheet lined with parchment paper.

Bake for 12 minutes or until edges begin to set.  Allow cookies to cool completely before adding icing.

To prepare icing, in a medium mixing bowl, beat powdered sugar, corn syrup, vanilla, and milk together.

Divide icing equally into three bowls. 

Add green food coloring to one bowl and add purple to another. Leave one bowl white.

Transfer the three colors to three small ziplock bags.  Cut a small corner off of each bag.

Squeeze frosting onto cooled cookies.  Depending on the consistency, you may have to spread it a bit with a knife.

Before frosting hardens, pipe three black circles on each cookie.

Using a toothpick, draw from the center of the cookie to the edge, creating a spider web design.

Allow frosting to harden.