1. Preheat oven to 350 degrees.
2. Whisk together flour, sugars, cinnamon, baking soda and baking powder in a large mixing bowl.
3. Add butter, egg whites, vanilla, sour cream and milk and mix on medium speed until smooth.
4. Stir in peaches.
5. Fill cupcake liners a little more than half way.
6. Bake 18-20 minutes.
7. Allow to cool for 1-2 minutes, then remove to cooling rack to finish cooling.
8. To make the icing, beat the shortening and butter until smooth.
9. Slowly add 3 cups of powdered sugar. Mix until combined.
10. Mix in 5 tbsp of peach puree.
11. Add the rest of the powdered sugar and mix until smooth.
12. Add more peach puree to get the right consistency and flavor. The more puree added, the thinner the icing will be. If it gets too thin, add more powdered sugar.
13. Ice cupcakes and top with peach slices if desired.