Line a baking sheet with a piece of parchment paper and preheat your oven to 350 degrees.
In a small mixing bowl, combine your butter, brown sugar and granulated sugar and mix well.
Mix in your vanilla extract and eggs.
In a separate mixing bowl, combine your flour, cocoa powder, baking powder and salt and mix into your butter mixture with a tablespoon of cream.
Fork the dough into ping pong sized balls, roll into a small bowl of sugar and place onto your lined baking sheet.
Bake for 10-12 minutes, unwrap your Peppermint Bells and press one gently onto the center of each cookie.