1. Preheat oven to 350 degrees and line pans with cupcake liners.
2. Sift cake mix into a small bowl and set aside.
3. In another small bowl, use a fork to finely mash bananas with baking soda and lemon juice.
4. In a large bowl, combine eggs, oil, vanilla extract, buttermilk and cinnamon.
5. Stir in mashed bananas.
6. Stir in cake mix until smooth.
7. Fill cupcake liners 3/4 full and bake for 17-22 minute or until an inserted knife comes out clean.
8. Buttercream: Beat butter until smooth. Add cocoa, vanilla, milk and cinnamon and beat again. Slowly add powdered sugar until you reach your desired consistency. Add more milk if needed.
9. Pipe onto cooled cupcake and top with banana chips! You can use fresh banana slices, but serve immediately or they will turn brown.