Making these delightful donuts can be simple if you follow these clear steps:

1. Prepare the Donut Dough: In a large bowl, mix the gluten-free flour, sugar, baking powder, and salt. In another bowl, whisk together the eggs, milk, vegetable oil, and vanilla extract. Combine the wet and dry ingredients until smooth.

1. Shape the Donuts: Use a donut pan or shape the dough into balls. If using a donut pan, fill each cavity about halfway. Alternatively, use your hands to form balls and create a hole in the middle.

1. Preheat the Air Fryer: Set your air fryer to 350°F (175°C) and let it preheat for about 5 minutes.

1. Air Fry the Donuts: Place the shaped donuts in the air fryer basket, leaving enough space between them. Cook for 8-10 minutes, or until golden brown. Remove and let cool on a wire rack.

1. Make the Custard Filling: In a saucepan, heat milk over medium heat. In a separate bowl, whisk together sugar and cornstarch. Once the milk is warm, slowly add to the sugar mixture, whisking continuously until thickened. Stir in butter and vanilla extract, then allow it to cool.

1. Fill the Donuts: Use a piping bag or a small hole in the end of each donut to inject the custard filling. Be generous for a delightful surprise!

1. Prepare the Chocolate Glaze: Melt chocolate chips and butter in a microwave-safe bowl, stirring until smooth. Dip the top of each custard-filled donut into the glaze, allowing excess to drip off.