Prepare the Cupcakes:

1. Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.
2. In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon. Set it aside.
3. In a large bowl, beat the granulated sugar and softened butter together until light and fluffy, about 2 minutes.
4. Add the eggs one at a time, beating well after each addition.
5. Mix in the sour cream, mashed bananas, and vanilla extract until combined.
6. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be sure not to overmix, or you’ll end up with dense cupcakes.
7. Divide the batter evenly among the cupcake liners, filling each about two-thirds full.
8. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
9. Allow the cupcakes to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely before frosting.

Make the Cinnamon Cream Cheese Frosting:

1. In a large bowl, beat the softened cream cheese and butter together until smooth and creamy, about 2 minutes.
2. Gradually add the powdered sugar, 1 cup at a time, and beat on low speed until well combined.
3. Add the vanilla extract and ground cinnamon, then beat on high speed for 1-2 minutes until the frosting is fluffy and spreadable.
4. Once the cupcakes are completely cool, frost them generously with the cinnamon cream cheese frosting using a piping bag or a knife.