Preheat the oven to 180°C (356°F).
Place almond flour and coconut flour into a bowl.
Mix in baking powder, salt, and erythritol together.
Add cold unsalted butter and mix evenly by hand.
Add almond milk and egg, then knead into dough.
Shape the dough into a round and divide into portions.
Place on a baking tray lined with parchment paper.
Bake in the oven at 180°C (356°F) for 20–25 minutes.