1. Preheat the oven to 350 F and spray a donut pan with non-stick spray.
2. In a large bowl, whisk together both flours, baking soda, baking powder, cinnamon, nutmeg and salt.
3. Place the almond milk, avocado oil, banana and spinach in a blender (in that order) and blend for about a minute or until the spinach is totally pureed. Add in the syrup and egg and blend for 15 more seconds.
4. Make a well in the middle of the dry ingredients. Pour the liquid ingredients in, stirring until just combined. Do not overmix!
5. Transfer the batter into a piping bag or a large Ziploc bag with the tip cut off, and fill each cavity of the donut pan until the cavities are each 2/3 full.
6. Bake for 10-12 minutes, or until the donuts spring back lightly when poked. Allow the donuts to cool for about 5 minutes in the pan, then remove and cool completely on a wire rack while you prepare the icing.
7. Combine the heavy cream, powdered sugar and vanilla extract in a medium sized bowl, and whisk until smooth; add more sugar if the icing is too thin or more cream if it is too thick.
8. Using a cake spatula, spread the icing onto the cooled donuts and top with sprinkles.

Donuts are best enjoyed fresh, but will keep at room temperature, in an airtight container for 2-3 days. If they are too warm, the icing may melt into the donut. I actually keep my leftovers in the fridge to avoid this!