Mint Chocolate Chip Cookies

In a medium bowl, whisk together the flour, cocoa, baking soda, and salt. Set aside.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together on medium-high speed until light and fluffy (approximately 2-3 minutes). Reduce the mixer speed to medium, add the egg and vanilla, and beat again until combined.
With the mixer on low, slowly add flour mixture and beat until just combined. Add the chocolate chips and continue mixing until evenly dispersed. Cover dough and chill in the refrigerator for at least 1 hour and up to 3 days.
When you are ready to bake the cookies, preheat the oven to 350ºF (177ºC). Line a large baking sheet with parchment or a silicone baking mat. Set aside.
Using a cookie scoop (I use this #50 cookie scoop for all of my standard size cookies), roll the dough into balls and place on prepared baking sheet. Bake for 10-12 minutes, or until edges are set and center is no longer shiny. Remove from the oven and allow to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely.

In a medium size bowl with a handheld mixer or a stand mixer fitted with the paddle attachment, beat the the butter on medium-high until smooth.
Turn the mixer to low, then slowly add the powdered sugar and mix until everything is combined. Add the vanilla extract, peppermint extract, milk or cream, salt, and green food coloring, then increase the mixer speed to medium and beat until combined. Add more coloring, if desired.
When the buttercream is your preferred color, add the mini chocolate chips and stir with a spatula to combine. Continue to stir the buttercream by hand to remove air bubbles and make it smooth and creamy. This usually takes about 3-5 minutes.
When your buttercream is smooth, use a small offset spatula to spread frosting onto each cookie, then sprinkle a few additional mini chocolate chips on top before the frosting sets. Cookies stay fresh covered at room temperature up to 1 week. Baked cookies can be frozen, up to 2 months. Rolled cookie dough can be frozen, up to 3 months. Place on baking sheet and add 1-2 minutes to baking time.