Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, combine butter with sugar until fluffy. Add in egg and mint extract, and mix until it is smooth.
Add in the flour mixture, and mix until it is fully combined. Add in the green food coloring, and mix until it is fully green. Fold in the chocolate chips.
Evenly divide the cookie dough between the prepared muffin cups. Bake for 12-15 minutes.