In a large mixing bowl, combine the cold cubed butter and sugar. Using a stand mixer or hand mixer, cream them together until the mixture is light and fluffy. This should take about 3–5 minutes.
Once the butter and sugar are well combined, add the mint extract and a drop of green food coloring if desired. Mix until everything is well incorporated.
In a separate bowl, whisk together the all-purpose flour and a pinch of salt. Gradually add the flour mixture to the butter mixture, mixing until just combined. Be careful not to overmix, as this can lead to tough cookies.
Gently fold in the Andes' Creme De Menthe Baking Chips using a spatula, ensuring they are evenly distributed throughout the dough.
Cover the dough with plastic wrap and refrigerate for at least 30 minutes. This chilling step is crucial as it helps the cookies maintain their shape during baking.
While the dough is chilling, preheat your oven to 350°F (175°C). Line baking sheets with parchment paper for easy cleanup.
Once the dough is chilled, remove it from the refrigerator. Use a cookie scoop or your hands to form small balls of dough, about 1 inch in diameter. If desired, roll the balls in additional sugar before placing them on the prepared baking sheets.
Bake the cookies in the preheated oven for 12–15 minutes, or until the edges are lightly golden. The centers may look slightly soft, but they will firm up as they cool.
Remove the baking sheets from the oven and let the cookies cool on the sheets for a few minutes before transferring them to a cooling rack to cool completely.
While the cookies are cooling, melt the dark chocolate chips with the vegetable oil or shortening in a microwave-safe bowl. Heat in 30-second intervals, stirring in between, until smooth and fully melted.
Once the cookies are completely cooled, dip the bottom half of each cookie into the melted chocolate, allowing any excess to drip off. Place the dipped cookies back on the cooling rack to set.
Once the chocolate has hardened, your Chocolate Dipped Mint Shortbread Cookies are ready to be enjoyed. Store any leftovers (if there are any!) in an airtight container at room temperature.
