Adding and Subtracting Volumes

Feeling creative, you decide to make a special Hershey's Kiss for you special someone. You start with a plain Ultimate (5 inch diameter) dark chocolate Kiss and want to add a layer of white chocolate around it. Assuming the Hershey Kiss is a cone, if you add the same volume of white chocolate as dark chocolate and maintain the iconic Kiss shape, how thick will the layer of white chocolate need to be?