Cream the butter and sugar together in the bowl of an electric mixer on low to medium speed (Use a paddle attachment). Mix until thoroughly incorporated – for about one minute. Scrape down the sides of the bowl with a plastic spatula and mix again for a few seconds more. Over mixing the butter and sugar in this step will cause too much air to be incorporated into the dough. If you’d like a light and fluffy cookie, that’s ideal, however the dough will spread more during baking; not ideal if you’d like the cookie to hold its shape.
Add eggs slowly and mix. Scrape down the bowl with your spatula at least once and mix again.
Add mint extract. Stir briefly.
Sift or whisk your dry ingredients together. (Flour and cocoa powder).
Add the dry flour mixture in 2 or 3 stages to the bowl and mix on low speed for about 30 seconds to 1 minute, and observe the dough mixing. When it starts to come together and the dough clumps around the paddle attachment and peels away from the sides of the mixer, it should be the right texture. You can also test the dough by pinching it between your thumb and index finger. If it’s soft but not sticky, it’s just right. If it’s too sticky when you pinch it between your fingers, add flour, ¼ cup at a time, and mix until you’re happy with the texture. (Different factors can affect the moisture of the dough, from the temperature of the butter you used, to water content of the butter, the actual ingredient brands you used, to the temperature of the room etc.).
Roll the dough out between 2 large pieces of parchment paper. Place on a baking sheet and into the fridge for a minimum of 1 hour.
Roll out the dough further if you need to, and cut out cookie shapes. Place on parchment paper-lined baking sheet. Re-roll scraps and repeat.
Put cookie dough shapes back into the fridge for 10 minutes to 1 hour to chill again. They will then hold their shape better when baked.
Preheat your oven to 350°F or 176°C.
Bake cookies for 8-12 minutes or until the center of the cookie no longer looks wet. The baking time will depend on the size of your cookie.
Let cookies cool to room temperature and decorate!