Preheat oven to 325°F and line a 9x13-inch baking pan with parchment paper.

Beat the softened butter and powdered sugar together until light and fluffy, about 2-3 minutes.

In a separate bowl, whisk together almond flour, rice flour, potato starch, and salt.

Add the vanilla extract to the butter mixture, then gradually mix in the dry ingredients until a soft dough forms.

Press the dough evenly into the prepared pan and prick all over with a fork.

Bake for 22-25 minutes until edges are lightly golden.

Let cool for 10 minutes in the pan, then slice into squares or rectangles while still warm.

Allow to cool completely before removing from pan.