With an electric mixer, cream together the butter, powdered sugar, and mint tea (cut open the bag and remove the leaves) until well combined.
In a separate bowl, sift together the flour, salt, and baking powder. Add half of the dry ingredients to the butter mixture, and mix until just combined. Add the remaining ingredients and mix until combined.
Divide the cookie dough in two, shape each portion into a flat disc, and wrap with cling wrap. Place the dough in the fridge for about 15 minutes.
While the cookie dough chills, preheat the oven to 375℉. Line two baking sheets with silicone baking mats and set aside.
Between two sheets of parchment paper, roll the dough out to a thickness of ⅛" or 3 mm. Place the cookie dough in the freezer, making sure it can lie flat. Repeat with the other portion of dough. Freeze for 5- 10 minutes.
Remove one portion of dough and cut out circles that are 2" in diameter and place on the prepared baking sheet. Bake for 10- 12 minutes, or until the cookies are just beginning to turn a light golden brown around the edge. While the first tray bakes, you can begin cutting out circles from the second portion of rolled out cookie dough.
Press your extra dough back into a disc, wrap, and chill while the first round of cookies bakes. Roll the dough out between parchment paper sheets, freeze, cut out circles, and bake. Repeat until all of the dough is used up.
Cool the cookies on the pan for just a few minutes before transferring to a cooling rack.