Preheat the oven to 180C/350F degrees.
Mix the peanut flour, erythritol, baking soda and salt together.
Add the eggs, coconut milk, butter, and vanilla extract. Blend until there are no lumps (you may find it easier if you use a blender).
Grease the donut tin with butter.
Fill the donut tin with the donut batter. Bake for 20 minutes until firm.
Allow to cool and remove from the tin.
Topping is optional.
Eat and enjoy!