Preheat the oven to 400°F. Line 3 baking sheets with silicone mats or parchment paper.

In a large bowl using an electric hand mixer or in the bowl of a stand mixer with the whisk attachment on, whisk together the two sugars and butter until light and fluffy. Add the eggs and vanilla extract. If making a full batch of mint chocolate chip cookies, add the peppermint extract now. Otherwise, wait. Once everything is well mixed, turn the mixer to low and add the whiskey until well-incorporated.

In a separate medium bowl, whisk together the flour, cornstarch, baking powder, and salt. Slowly add it the the wet mix, whisking together on medium-low. Stop the machine and scrape down the sides with a rubber spatula, if necessary. Once fully mixed together, add in the green food gel coloring until you achieve the desired color of green.

If making a half a batch of chocolate mint cookies, remove half of the dough and place in a medium bowl. Return the stand mixer bowl back to the machine and add in the peppermint extract. Whisk together on high.

To the NON-mint bowl, add in the milk chocolate chips and mix together with a wooden spoon. In the MINT bowl, add the dark chocolate and mix together with a wooden spoon or on high speed with the whisk.

Spoon 2 to 3 tablespoons of cookie dough per cookie and roll gently into a ball. Place the cookie dough balls onto the baking sheet, about 2 inches apart. Bake one sheet at a time for about 10 to 12 minutes (10 minutes for softer cookies ~ NOTE: they will seem very gooey but will firm up as they cool). Let the cookies cool for about 5 to 10 minutes on the sheet before placing them on a wire rack to cool completely.

Enjoy!