1. Preheat and Prep Pan:

• Preheat your oven to 350°F (175°C). Grease your donut pan with butter or non-stick spray.

2. Mix Dry Ingredients:

• In a large bowl, whisk together the flour, sugar, salt, and baking powder. Set aside.

3. Combine Wet Ingredients:

• In a separate bowl, mix the melted butter, egg, sourdough starter, and milk until smooth and well combined.

4. Make the Batter:

• Gradually pour the wet ingredients into the dry ingredients. Stir gently until just combined. Avoid overmixing to keep the donuts light and fluffy. A few lumps in the batter are fine.

5. Optional Long Fermentation:

• For extra flavor, refrigerate the batter for 8–12 hours. If skipping this step, proceed directly to baking.

6. Fill the Pan:

• Transfer the batter to a piping bag or a zip-top bag with the corner cut off. Fill each donut well about ¾ full.

7. Bake the Donuts:

• Bake for 15–17 minutes, or until the donuts spring back when lightly pressed. The bottoms should be golden brown. Avoid overbaking.

8. Cool and Coat:

• Let the donuts cool in the pan for a few minutes, then transfer to a wire rack to cool completely.
• For Powdered Sugar Coating: Toss cooled donuts in powdered sugar until evenly coated.
• For Vanilla Glaze: Whisk together 1 cup powdered sugar, 1 tsp vanilla extract, and 2–3 tbsp milk or cream. Dip the tops of the donuts into the glaze and let set on a wire rack.