Pour the warm milk into the bowl of a stand mixer.
Sprinkle the yeast and then the sugar into the milk. Gently stir.
Let the yeast bloom for about 5 minutes. It should get very bubbly and frothy looking.
Then pour in the salt and coconut oil. Put the dough hook attachment onto the stand mixer and begin mixing.
Add the cornstarch and then begin adding the flour about 1/2 cup at a time, letting the dough hook mix until the dough comes together and forms a ball.
Then let the dough hook knead the dough for 1 to 2 minutes or until the dough is smooth and no longer sticky.
Remove the dough ball from the bowl and then spray the bowl with non-stick spray. Put the dough back in the bowl. Cover the bowl with a kitchen towel and then let the dough rise in a warm place for 45 to 60 minutes or until the dough has doubled in size.
Punch the dough down and then turn it out onto a floured surface. Roll the dough out until it is about 1/2 an inch thick.
Cut the dough into circles with a biscuit cutter or cup. Then cut small circles out of the center to form the donuts. Save the donut holes, you can air fry them too.
You should get 12 to 14 donuts and donut holes. Leave them on the counter where you rolled them out. Cover them all with a kitchen towel. Let them rise for 25 to 30 minutes.
Spray the basket of an air fryer with non-stick spray. Then place a few donuts and donut holes into the air fryer at a time. Spray the tops of the donuts with more non-stick spray.
Air fry the donuts at 390 degrees(F), for 3 to 4 minutes or until they are golden brown. Repeat with all the donuts.
Make the glaze, whisk together the powdered sugar, vanilla and milk until smooth. Dip the donuts into the glaze and leave as is, or...
Stir together the cinnamon and sugar and glaze the donuts and then coat in the cinnamon a sugar. Then eat!