Preheat the oven to 170°C (338°F).
In a bowl, mix almond flour, oatmeal flour, and baking powder.
Add erythritol, egg, vanilla extract, and unsalted butter, then mix well.
Gather all ingredients into one dough, divide into portions, and shape into round balls.
Line a baking pan with parchment paper and place the cookie dough balls on it.
Bake in the oven at 170°C (338°F) for 13–15 minutes.
Cool and serve.