In a large bowl, combine dry cake mix and remaining ingredients except ingredients for Cinnamon Frosting. Beat with an electric mixer on low speed for 3 minutes. Fill greased muffin tins 2/3 full. Bake at 350 degrees for 22 to 25 minutes. Let cool.
Prepare Cinnamon Frosting: beat butter until fluffy. Mix in vanilla, cinnamon and powdered sugar. Stir in enough milk for desired consistency. Frost cupcakes with Cinnamon Frosting.