Mummy Sandwich Cookies with White and Dark Chocolate

Fill a medium pot with 2 inches of water, place over medium heat, and bring to a simmer. Place dark chocolate in a heatproof metal or glass bowl and set over the pot (the simmering water should not touch the bottom of the bowl). Melt chocolate, stirring frequently, until almost completely melted. Remove bowl from heat, and stir until smooth. Using a small offset spatula or spoon, apply a thin layer of dark chocolate onto the rounded surface of the "tops" of half the cookies, reserving the remaining half of the cookies for the sandwich "bottoms." Reserve remaining dark chocolate for the mummy eyes. Set cookies aside to allow chocolate to set, about 10 minutes. Repeat melting process with white chocolate. Fill a pastry bag fitted with a small tip with melted white chocolate. Drizzle thin horizontal stripes of white chocolate onto each chocolate-covered cookie, leaving a 1/4-inch gap in the center for the eyes. Add the whites of two eyes in the center of each cookie and allow to set, about 5 minutes. Using a toothpick, add two small dots of reserved melted dark chocolate to the eyes to make pupils. Repeat with remaining cookies.