Preheat your oven to 160°C (320°F).
In a mixing bowl, add the room temperature salted butter and powdered sugar. Using an electric mixer, beat until light and fluffy (about 2-3 minutes).
Add the pure vanilla extract to the mixture and mix until well combined.
Sift together the potato starch and cake flour in a separate bowl. Gradually add to the wet ingredients, mixing on low speed to avoid flour clouds until just combined.
Shape the dough into small balls (about 1 inch in diameter) and place them on a baking sheet lined with parchment paper, spacing them about 2 inches apart.
Bake for 15-18 minutes or until the edges are lightly golden. The centers may appear soft, but will firm up as they cool.
Let the cookies cool on the baking sheet for a few minutes before transferring to a cooling rack. Dust with powdered sugar once completely cooled.
