Preheat the oven to 350°F (176°C). Line the baking sheet with parchment paper.
In a mixing bowl, beat the butter and powdered sugar until creamy, light, and fluffy. Add the vanilla extract and stir well. Fold in the potato starch and cake flour, mixing well until a soft dough is formed.
Divide the dough into 2 rounds. Use your palms to shape them into small balls. To create a pattern on the cookies, use a fork to press gently onto the top of the round cookies. Dip the fork in water after each press to prevent the cookie dough from sticking to it.
Place the baking sheet in the bottom part of the oven. Bake for about 10 minutes, or until the cookies turn very light brown. Remove from the oven and let cool for about 5 minutes. Dust some powdered sugar over the cookies before serving.
Notes
Potato starch and potato flour are completely different. Make sure you get potato starch for this recipe. In baking, potato starch adds a feather light texture to cookies.