In a glass measuring cup, add warm water, sugar and yeast. Stir.
Let the yeast sit until it proofs and is puffy. Set aside.
In a large bowl, sift together flour, baking powder, baking soda, salt and sugar.
Cut in the shortening until mixture is crumbly.
Stir in the buttermilk and yeast mixture until a dough forms. (Add a bit more flour if the dough is too wet to handle.
Flour a work surface and place the dough on the surface.
Flour your hands and knead dough several times until dough is smooth and elastic.
Divide dough into 20-25 pieces and roll into small balls. (can also make mini twists or mini donuts)
Dip balls into butter and then place into the greased air fryer basket.
Cook on 325 F. for 4 minutes. Let donuts sit in air fryer for an additional 1-2 minutes before removing.
Remove from air fryer and immediately dip into the butter, letting excess drip off.
Then coat in the cinnamon-sugar mixture.
Repeat until all the balls have been cooked and coated.
Serve warm or room temperature.