Combine flour, baking powder, baking soda, salt, and nutmeg in a bowl. Set aside.
Combine sugar, eggs, milk, vanilla extract, and melted butter in a separate bowl. Mix thoroughly.
Add dry ingredients to wet ingredients and stir until just mixed----do not over-mix the batter.
Lightly spray donut pans with nonstick cooking spray.
Fill a gallon-sized plastic bag with donut batter. Cut a hole in one corner and gently squeeze the batter into each donut cavity.
Bake donuts for 11-13 minutes or until a toothpick inserted comes out clean.
Let donuts cool in the pan for 5-7 minutes then transfer the donuts to a cooling rack.
Pour powdered sugar into another gallon-sized plastic bag. Add a warm donut then shake to cover the donut completely with powdered sugar. Place the sugar-covered donut back onto the cooling rack. Repeat with remaining donuts.Allow donuts to cool completely.Note: If there are any areas that look bare (the powdered sugar may soak into the donuts due to moisture) you can sprinkle them with a little more powdered sugar.
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Notes
Because of the moisture in the donuts, the powdered sugar will eventually soak into the donuts. You can toss them again in powdered sugar on day 2 or sprinkle with more powdered sugar.These are best eaten the day they are made. Store donuts in an airtight container with paper towels between each layer to keep them fresh.