Whisk together flour, baking powder, and salt in a medium bowl.

Combine melted butter, sugar, buttermilk, egg, sour cream, and vanilla extract in a large bowl. Whisk until you achieve a smooth mixture.

Add the dry ingredients to the wet ingredients and stir until just combined. Stop mixing as soon as the ingredients come together.

Toss frozen blueberries with 1 tablespoon of flour, then fold them gently into the dough.

Cover the bowl and refrigerate the dough for 30 minutes.

Roll the chilled dough into 1-tablespoon portions and shape them into balls. Place the balls on a parchment-lined tray.

Preheat your air fryer to 350°F (175°C) for 3–5 minutes.

Line the air fryer basket with a single sheet of parchment paper. Arrange donut holes in a single layer, making sure you leave space between each piece.

Air fry for 8-10 minutes, flipping the donuts halfway through cooking, until they turn golden brown. Repeat this process with any remaining dough.

Make the glaze by whisking powdered sugar, milk, and strained blended blueberries until smooth. Adjust the consistency by adding more milk or powdered sugar as needed.

Dip the warm donuts into the glaze and place them on a wire rack or parchment-lined surface to set.