Preheat the oven to 375 degrees F.

In a large bowl mix the butter and sugar with an electric whisk or beaters until well combined. Drop in the egg, vanilla, peppermint, and salt and continue mixing. Reduce the speed to low and add in the cocoa powder and flour until well blended. Scrape the sides of the bowl as needed.

Pack the dough into the cookie press and fit it with your desired design plate. Press the dough onto ungreased cookie sheets (if the dough is too cold it won't "release" from the press onto the cookie sheet very easily). Continue pressing out cookies using as many different design plates as you'd like (that's the fun part!) spacing the cookies about 1" apart.

Bake until firm to the touch, about 10 minutes. Cool on drying racks and store in an airtight container for up to 5 days. Alternatively you could freeze them for later!