In a medium microwave-safe bowl, combine chocolate and butter.

Microwave in 30-second intervals, stirring well between each, until melted and smooth. Set aside to cool slightly.

In another medium bowl, combine flour, sifted cocoa powder, baking powder, and salt. Whisk to mix and set aside.

In the bowl of an electric mixer fitted with a paddle attachment, mix together brown sugar, eggs, peppermint extract, and vanilla.

Add the melted chocolate mixture to the mixer and combine.

Gradually add the flour mixture at low speed, mixing until just combined.

Cover the bowl and chill the dough for 1 hour, or until firm enough to handle. (For quicker chilling, divide the dough into two containers.)

During the last 15-16 minutes of chilling, preheat your oven to 325°F (163°C).

Scoop out slightly heaping tablespoons of dough, roll them into balls, and place them on a baking sheet lined with parchment paper or a silicone mat, spacing them 2 inches apart. Keep the remaining dough chilled.

Bake the cookies for about 10 minutes, until they are slightly under-baked.

While the cookies bake, use kitchen scissors to cut marshmallows in half.

Remove the cookies from the oven, place one marshmallow half on each cookie with the cut side down.

Return the cookies to the oven and bake for an additional 3 minutes, or until the marshmallows start to melt.

Gently press down on the marshmallows to flatten them slightly.

Let the cookies cool for a few minutes on the baking sheet, then transfer them to wire racks set over a baking sheet to cool completely.

Sift together the sugar and cocoa powder in a medium mixing bowl and set aside.

In a saucepan over medium heat, combine the butter and cream. Stir frequently until the butter melts and the mixture simmers.

Remove from heat, then whisk in the sifted sugar and cocoa powder until smooth.

Stir in the peppermint extract.

If the icing is too thick, add a little hot water to thin it; if it’s too thin, add more sifted sugar to thicken it.

Spoon icing over the cookies immediately (or drizzle from a resealable bag with a cut corner). After icing, sprinkle each cookie with crushed peppermint before the icing sets.