Special equipment: You'll need a piping bag with a plain 1/2-round tip.
Heat the oven to 350 degrees F. Line three sheet pans with parchment.
Make the cookies: Melt the butter over simmering water in a small saucepan over medium heat. Once melted, remove from the heat, add the chopped chocolate and stir until melted. Set aside in a warm place.
In a stand mixer fitted with the whip attachment, whip the brown sugar and eggs on high speed until thick and ribbony, 3 to 4 minutes. Add the ground espresso and both extracts and whip for another 3 minutes. With a rubber spatula, fold in the warm chocolate/butter mixture. Stir to combine.
Sift together the flour, salt, cinnamon and baking powder. Fold the dry ingredients into the chocolate mixture, then fold in the chocolate chips.
Using a small ice cream scoop or a heaping teaspoon, scoop the cookies onto the sheet pans, leaving 2 inches in between. Bake until the tops become shiny and start to crack, 7 to 8 minutes. Do not overbake. Let the cookies cool completely on the pan before filling.
Make the peppermint cream: Heat the cream in a small saucepan over low heat until it comes to a simmer. Do not boil. Remove the pan from the heat and stir in the chocolate, both extracts and the salt. Let the mixture cool in the refrigerator for about 1 hour. Check the texture-it should be pudding-like.
In a stand mixer fitted with the whip attachment, whip the chocolate cream on medium speed until slightly firm peaks form. With a rubber spatula, fold in the crushed peppermints.
Spoon the filling into the piping bag and pipe it on the undersides of half of the cookies. Arrange another cookie on top. Sprinkle with confectioners' sugar.
Once filled, serve the cookies right away. If there are leftovers, store at room temperature in an airtight container for up to 1 day. Store unfilled cookies in an airtight container for up to 3 days.