In a large bowl, combine yeast, sugar, and milk. Let it sit for about 5 minutes (after this time the yeast should start foaming)
Once the yeast mixture starts foaming, add the melted butter, vanilla, and egg. Mix ingredients well.
Combine the flour and cinnamon. Add to the yeast mixture and mix until they are fully integrated and a soft dough forms.
Transfer the dough to a floured workspace and knead the dough for about 4 minutes or until smooth.
Place the dough in a large oiled bowl, cover it with a towel, set it in a warm place, and let it rest for about 2 hours or until doubled in size.
Remove the dough from the bowl. Place on a floured surface, roll into logs then cut it into 18 small pieces. DO NOT PUNCH THE DOUGH DOWN.
Shape the pieces into balls and place them on a baking sheet and let them sit for about 40 minutes.
When ready to air fry, preheat the air fryer to 375°F for 5 minutes.
Place the donut holes in the air fryer basket being careful not to overcrowd. It may take more than one batch. Cook for 6-8 minutes or until golden brown.
Cinnamon Sugar Coating
Use a small bowl to combine the sugar and cinnamon.
Place the butter in a microwave-safe dish and microwave on high for about 20-30 seconds or until butter has melted.
While still warm, roll the donuts in melted butter then in the cinnamon sugar mixture. Note: If you like a lighter cinnamon sugar coating, skip the butter and just roll in the cinnamon sugar mixture.
Serve warm or let them cool and store in an airtight container.
Notes
RECIPE TIPS
If your yeast doesn't bloom, it may be dead. Throw it out and try again with a new packet.
If using rapid rise yeast, you can skip the 5-minute rest for the yeast to bloom.
Get the milk to the right temperature to activate the yeast. It should be between 100 and 110°F.
For a lighter coating of cinnamon sugar, skip rolling the air-fried donut holes in butter.
Be sure to leave space between the donut holes in the air fryer so they cook evenly.