Combine almond flour, baking powder, and erythritol in a bowl and mix well.
Add egg, melted butter, and vanilla extract; mix until a dough forms.
Chop walnuts, almonds, and other nuts coarsely and mix into the dough.
Shape the dough into a round, place it on a pan, and flatten slightly.
Bake in a preheated oven at 180°C (356°F) for 20 minutes.