Copycat Swig Cookies

Preheat the oven to 325°F/160°C, or 140°C for a fan oven, and line 2 cookie sheets with parchment paper or Silpat silicone mats.
In a bowl, combine the flour with baking soda, cream of tartar, and salt and set aside.
In a mixing bowl, combine butter with sugar and beat with hand mixer until smooth and creamy (about 2 minutes). Then add the oil and powdered sugar, and beat again for a minute.
Add the egg and beat until smooth. Add the dry ingredients to the wet ingredients, and mix on LOW speed until combined.
Using a large 3 tablespoon cookie scoop, scoop the dough onto the prepared cookie sheets.
Spray the bottom of the clean glass (around 2.5” in diameter) with baking spray, then press each cookie to flatten it until it’s around ½” in thickness. The edges of the cookie dough should flare out and become uneven.
Bake in the preheated oven for 11 minutes. You don’t want the cookies to brown. Remove from the oven and allow to cool on the cookie sheets for 5 minutes, then carefully transfer to a wire rack to cool completely.
To make the frosting, in a mixing bowl combine butter with sour cream and with a hand mixer beat until creamy. Add the powdered sugar, and beat on LOW speed until combined and then increase the speed and beat for another minute. Add food coloring, and mix again.
Frost the cookies using a butter knife or the back of a spoon.