Preheat your oven to 350°F (175°C).

In a large mixing bowl, combine the all-purpose flour, granulated sugar, baking powder, baking soda, salt, and ground cinnamon. Use a whisk to mix until well combined.

In another bowl, cream the softened butter. Add in the eggs, one at a time, and mix well. Then, stir in the vanilla extract, sour cream, and mashed banana until smooth and creamy.

Pour the wet mixture into the dry ingredients and stir gently with a spatula until just combined. Avoid over-mixing.

Fold in the chopped pecans.

Line the muffin tin with cupcake liners and fill each liner about two-thirds full with the batter.

Bake for about 20-25 minutes, or until a toothpick inserted into the center comes out clean. Let them cool on a wire rack.

Prepare the cream cheese frosting by mixing the softened cream cheese and butter until creamy.

Gradually add the powdered sugar, vanilla extract, and ground cinnamon, mixing until smooth.

Spread the frosting on top of each cooled cupcake and sprinkle chopped pecans for decoration.