Preheat oven to 350˚
Lightly grease a donut pan. Set aside.
Whisk together egg, cashew butter, maple syrup, milk, and vanilla until smooth. Slowly add almond flour, tapioca flour, and coconut flour and mix until combined.
Once they are cool enough to handle, brush each donut with some melted vegan butter then generously dunk into the bowl with the cinnamon sugar topping, making sure to coat well on all sides. Serve and enjoy!