Preheat oven to 350℉.
In a medium mixing bowl use a whisk to combine dry ingredients: almond flour, cassava flour, tapioca flour, maple sugar, baking soda, Saigon cinnamon, salt. 
 In a large mixing bowl use a whisk to combine wet ingredients: eggs, neutral oil, dairy free milk, pure vanilla, apple cider vinegar. 
 Add dry ingredients to wet ingredients and use a whisk to mix until fully combined and smooth. 
 Use cooking spray or baking brush to brush neutral oil on donut pans. 
Use a measuring cup or large pastry bag to fill donut cavities about ⅔ full. 
 Bake in preheated oven about 15 minutes until browned and toothpick comes out clean or with a few crumbs.  
 While donuts are baking mix the cinnamon sugar blend in a shallow bowl or rimmed plate.
 Make the optional icing. In a medium bowl add powdered sugar, vanilla and 1½ tablespoon dairy free milk. Use a fork to combine until smooth. Add more milk ½ tablespoon at a time to reach a smooth but thick consistency. Store in a small piping bag, sandwich storage bag, or airtight container. 
When cool to touch create defined wholes if you desire** and roll in cinnamon sugar mixture to fully coat. 
 Drizzle with icing if desired.