Preheat the oven to 350 (180 C).

In a small bowl, place the almond flour, coconut flour, baking soda and salt.

In a large bowl, cream the butter, egg, and vanilla extract with an electric mixer or handheld beater until smooth.

Add the sweetener and mix in with the beater.

Add the dry mixture to the butter mixture and mix until combined.

Roll 2 tablespoonfuls of the mixture into balls and place on baking trays lined with parchment paper. Press to flatten. Bake for 10–12 minutes or until golden. Allow to cool on the trays for a few minutes and then transfer to a wire rack to cool completely.