Fill a pastry bag with melted chocolate and cut the tip. Draw the faces on the M&M's and when it's hardened, you're done.
Here, I decorated a gravestone-shaped chocolate cookie with chocolate coating on a skewer. The skeleton and lettering are made with white chocolate.
Story Behind this Recipe
I came up with these Halloween decorations using a 1.5kg/3lb bag of M&M's.
I don't recommend using commercially available chocolate writing pens because the tips are too thick. Use a homemade pastry bag or small sandwich bag with a narrow tip. The pastry bag I used in Step 1 is a clear wrapping sheet cut into a small triangle. Parchment paper would also work.