Preheat oven to 350º.
Spray your donut pan with cooking spray.
In a large bowl, whisk together the first seven dry ingredients, flour through sugar.
In another small bowl whisk together the melted and cooled butter, vanilla, egg yolks, and apple cider. Make a well in the center of dry ingredients and pour in. Mix gently.
In a separate small bowl whisk the two egg whites for about a minute or two with a fork. You are just trying to get them a bit thicker so they add some fluffiness to the doughnuts.
Add egg whites to mixture and stir just until mixed.
Transfer mixture to a Ziploc bag and cut the corner tip off. This makes it easy to pipe into the donut pan.
Fill each well ½ full without covering the middle section. If you do, your doughnuts won't have a hole.
Cook for about 8-10 minutes.
Allow to cool completely before glazing.
For the icing simply mix the powdered sugar and the maple syrup. Add milk a little bit at a time to get the desired consistency. More milk will make icing runny so don't add too much at one time.
Dip doughnuts in icing and place on a rack to drip dry. Top with sprinkles before the icing sets.
If you are using a donut pan, preheat oven to 350° and bake for 8-10 minutes.