Preheat oven to 180C.
Melt the butter in saucepan until melted and hot over medium heat. Place the melted butter and erythritol in a mixing bowl and beat until combined. Add the vanilla and egg, and beat on low for another 15 seconds.
Add the almond flour, baking powder, xanthan gum and salt. Beat until well combined.
Press the dough together and remove from the bowl. Knead in the chocolate chips with your hands or a silicone spatula.
Use a small ice cream scoop to divide and shape the dough into 12 portions and place on a lined baking tray. Bake for 10-12 minutes at 180C (360F). The cookies will look a little undercooked when removing from the oven, but after cooling they will harden.
If cookies have not flattened after 6-7 minutes in the oven, press down with the back of a fork.
Allow to cool for 15 minutes before serving. Keep in an airtight container for up to 7 days.