In a large mixing bowl, beat together the unsalted butter and granulated sugar on medium speed until creamy, about 1 minute. Add the peppermint extract and mix until combined.

In a separate bowl, sift together the all-purpose flour, cocoa powder, and salt. Gradually add the dry mixture to the butter and sugar mixture until a thick dough forms.

Shape the dough into a disc, wrap in wax paper, and chill in the refrigerator for 30 minutes.

Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.

Roll out the chilled dough on a floured surface to ¼ inch thickness and cut into rectangles measuring 1 inch by 2 inches.

Bake the cookies in the preheated oven for 11 to 13 minutes until edges are set but centers are soft. Allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.

Melt the chocolate melting wafers in a microwave-safe bowl in 30-second intervals, stirring until smooth.

Dip each cooled cookie halfway into the melted chocolate and sprinkle optional toppings before the chocolate sets. Allow the cookies to harden at room temperature.