Preheat oven to 350. In a stand mixer combie 1 cup of softened unsalted butter, 1 cup brown sugar, one cup white sugar and 2 1/2 tsp vanilla. Scrape down edges as needed. Mix on medium high until well mixed and fluffy. Add 2 eggs and 4 tbsp milk and mix until combined.
In a separate bowl mix 2 cups flour, 2 tsp baking soda, and salt.
Slowly mix dry ingredients into wet ingredients on low speed until well combined.
Fold in 2 cups of mint chips, and 1 cup of semi sweet chocolate chips. Allow dough to chill in refrigerator for about 1 hour. Spoon 2 tbsp scoops of dough onto a nonstick baking sheet. (feel free to use parchment or silicone if you prefer). Bake in oven for 10-12 minutes.