Firstly, mill the flour.
To the flour, add baking powder, baking soda, and salt. Then, stir to combine.
Preheat the oven to 350*F.
Spray your donut pans with oil.
Blend the Blueberries in a blender or food processor until smooth.
Then, pour the blueberry puree into a large mixing bowl.
Add melted butter, oil, sugar, eggs, yogurt, and vanilla to the blueberry puree, and mix until combined.
Then, add the dry ingredients into the wet ingredients, stir until smooth.
In you sprayed donut pan, pour batter into the donut pan wells about 3/4 full. (Don't overfill.) (Picture shows batter being poured into a piping bag.)
I really like to use a piping bag to put the batter into the pan, but it is not necessary.
Bake on the center rack of the oven for about 12-14 minutes.
Once baked, let the donuts cool in the pan for about 10 minutes.
Then, remove the donuts onto a wire rack to finish cooling, this normally takes about 20 minutes or so.
While the donuts are cooling, you can make the glaze. (*glaze is optional)
To make the glaze, mix powdered sugar, salt, vanilla, and part of the whole milk. Stir to combine and whisk until smooth. If the glaze is too thick add the rest of the milk a little at a time until it thins out to a drizzle consistency.
Once the donuts have cooled to room temperature, dip each side into the glaze. Allow the excess glaze to run back into the bowl. Transfer donuts to a wire rack to dry.
Lastly, Enjoy!