Cream the butter and sugar together in a medium sized mixing bowl. Beat in the eggs and add the vanilla; stir until combined. 

Sift in the flour and cocoa, and mix/knead until the mixture is well combined. Cover, and chill for 2 hours or overnight.

On a large flour dusted work surface, roll the dough to about 1/4" thickness. Cut into shapes and lay out on parchment lined or ungreased (non-stick) cookie sheets (the cookies can be fairly close together since they don't spread very much).

Bake at 350 degree F for 8-10 minutes or until done. Cool on wire racks.

In a glass bowl, melt the dark chocolate wafers over a pan of simmering water (making sure the bottom of the bowl doesn't touch the water), or in the microwave for 30 seconds at a time, stirring each time, until all of the wafers are melted and smooth.

Note: If you are using the microwave, if the bowl begins to feel hot, allow it to sit on the counter until it feels barely warm before microwaving the chocolate again.

Dip the bottom of each cookie into the bowl of melted chocolate, and turn each cookie to its side with your fingers to let some of the chocolate drip off the bottom. Set the cookies chocolate side down onto a cookie sheet lined with wax paper or parchment paper.

Scrape the remaining dark chocolate into a piping bag, ziploc bag, or heat proof squeeze bottle. If using a bag, cut off the tip, and drizzle the tops of the cookies with chocolate.

Melt the white chocolate in another small glass bowl, as before. Scrape the chocolate into another bag or squeeze bottle, and drizzle the tops of the cookies.

Allow the chocolate to set before trimming away the excess chocolate. Store in a cool, dry place in an airtight container.