Preheat oven to 350 degrees and line muffin pans with liners (12).
Using mixer fitted with a paddle attachment beat butter and sugar until fluffy.
On low-speed add eggs and egg white and beat until fully mixed in.
In a medium bowl sift flour, baking soda, baking powder, salt, cinnamon, and nutmeg together. (Instead of sifting, you can run a whisk through the ingredients. Essentially accomplishes the same thing- aeration and removal of clumps- without making a mess.)
Mix sour cream, milk, and vanilla together.
Add 1/3 of dry ingredients to mixer, then 1/2 of wet. Followed by another 1/3 of dry. Finish with remaining wet and dry ingredients. Careful not to overmix.
Fold in blueberries and fill muffin liners 3/4 full. Bake 18-20 minutes or until very tops are fully cooked.
To make frosting, beat butter and cream cheese until fluffy. Add maple flavoring and sugar and beat until smooth.
Cool cupcakes before frosting. Use a pastry bag fitted with a large star and swirl around the outer part of cupcake and gradually come inwards with each swirl. Or just slather it on there.
Decorate with blueberries.