In a large bowl, whisk together 1 cup all-purpose flour, ¼ cup granulated sugar 1 tsp baking powder, ¼ tsp salt, and optional ¼ tsp ground cinnamon until well combined.
In a separate bowl, mix ⅓ cup milk, 2 tbsp melted butter and ½ tsp vanilla extract.
Gradually add wet ingredients to the dry ingredients, stirring until a soft, slightly sticky dough forms.
Lightly flour your surface, roll out the dough to about ½-inch thickness, and cut donut shapes using a donut cutter or two round cutters. I used a donut pan, that fit into my air fryer, but the other suggestions are in case you don't have one.
Preheat your air fryer to 350°F (175°C) for 3–5 minutes.
Spray the air fryer basket with non-stick cooking spray. Place donuts in a single layer, making sure they don’t touch. Air fry for 5–6 minutes, until lightly golden and cooked through.
Let donuts cool slightly. Optionally, dust with powdered sugar, cinnamon sugar, or drizzle with glaze before serving.