Pre-heat oven to 350° (180° celsius). Lightly grease and flour a 6 donut hole baking pan.
FOR THE DONUTS
In a medium bowl whisk together flour, baking powder, baking soda, salt, and sugar.
In a medium bowl stir together melted butter, egg, greek yogurt and milk until combined then add zucchini and stir gently to combine.
Add wet ingredients to dry ingredients and mix just until smooth.
Pour batter into a pastry bag with a round tip, or with a spoon fill the donut pan almost full. Bake approximately 10 minutes. Let cool completely before frosting.
FOR THE FROSTING
Whisk powdered/icing sugar, cream cheese, vanilla and milk until smooth. Spread on cooled donuts. Enjoy!
Notes
As long as the donuts are stored (without frosting) in an airtight container, they will last 2 days at room temperature. If they are frosted then place in an airtight container and refrigerate, they should keep for 6-7 days.They can also be frozen, be sure to place in an airtight freezer container or bag. They will last 2-3 months. Of course any mouldy donuts should be thrown out.