Directions :

1. Grease a large bowl with cooking spray. In a small, microwave-safe bowl or glass measuring cup, add milk. Microwave until lukewarm, 40 seconds. Add a teaspoon of sugar and stir to dissolve, then sprinkle over yeast and let sit until frothy, about 8 minutes.
2. In a medium bowl, whisk together flour and salt. In a large bowl, whisk together remaining ¼ cup sugar, butter, egg, and vanilla. Pour in yeast mixture, mix to combine, then add in dry ingredients, stirring with a wooden spoon until a shaggy dough forms.
3. Transfer to a lightly floured surface and knead until elastic and only slightly tacky, adding more flour a teaspoon at a time if needed, about 5 minutes. Form into a ball then place dough in oiled bowl and cover with a clean dish towel. Let dough rise in a warm spot until doubled in size, about 1 hour.
4. Line a large baking sheet with parchment paper and lightly grease with cooking spray. Punch down dough, then turn onto a lightly floured work surface and roll out into a ½" thick rectangle.
5. Using a doughnut cutter or 3" and 1" biscuit cutters, punch out your doughnuts. Knead any scraps together and punch out more doughnuts or holes. Place doughnuts and holes onto baking sheets, cover with dish towel, and let rise again, 40 minutes to 1 hour more.
6. Grease basket of air fryer with cooking spray and add 2 doughnuts and 2 doughnut holes at a time, making sure doughnuts don’t touch. Cook at 375° for 6 minutes, until deeply golden. Place on cooling rack and repeat with remaining dough.
7. Dip doughnuts in glaze (see below) or follow instructions for cinnamon sugar. Return to cooling rack and let set for 5 minutes before serving.
8. In a medium bowl whisk together powdered sugar, milk, and vanilla until smooth.
9. In a medium bowl whisk together powdered sugar, cocoa powder, and milk.
10. In a large shallow bowl, whisk together cinnamon and sugar. Brush doughnuts with melted butter and toss in cinnamon sugar.