Gather all your ingredients and ensure the butter is softened to room temperature. Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a mixing bowl, whisk together the flour, cocoa powder, baking soda, and salt until evenly combined.

In a separate bowl, cream together the softened butter and granulated sugar until fluffy and light in color, about 3-5 minutes.

Beat in the large egg and peppermint extract to the creamed mixture until fully incorporated.

Gradually add your dry mixture to the wet mixture, starting at low speed to avoid a flour explosion. Increase the speed until a soft dough forms.

Roll the dough into small balls, about 1 inch in diameter, and place them onto the prepared baking sheet, spacing about two inches apart. Gently flatten each ball with the bottom of a glass.

Bake in the preheated oven for 10-12 minutes, until edges are firm and centers are slightly soft. Let cool on the baking sheet briefly before transferring to wire racks.

Melt dark chocolate chips and coconut oil together in a microwave-safe bowl, heating in intervals until smooth.

Dip each cooled cookie into the melted chocolate until fully coated, allowing excess to drip off.

Drizzle additional melted chocolate or sprinkle with mint extract for decoration. Let cool until chocolate hardens.