1. Preheat the oven to 350F. Grease a PADERNO Professional Non-Stick Donut Pan, 6-Cup lightly with baking spray.
2. Combine the flour, baking powder, salt, cinnamon and nutmeg together in a mixing bowl. In a separate bowl, whisk the melted butter and egg, then whisk in the sugar, milk, sour cream and maple extract. Add the egg mixture to the flour mixture and stir well to combine. Transfer to a large zip-top bag.
3. Cut one corner off of the bag, creating a large hole. Squeeze the batter into the prepared pan, dividing the mixture evenly between all the cups. Bake for 10 - 12 minutes or until puffed, golden on the bottom and cooked through. Flip doughnuts out onto a rack set over a baking sheet and glaze them immediately.
4. While the doughnuts bake, make the glaze. Combine the butter and maple syrup in a small pot over medium heat. When the butter melts, add the icing sugar and maple extract and whisk well to combine. Keep warm.
5. Dip warm doughnuts into warm glaze or spoon warm glaze over hot doughnuts. Let cool then sprinkle with flaky salt, if you like.
TIP: Maple extract gives these treats that unforgettable doughnut-shop taste!