Preheat the oven and line a cupcake pan with cupcake liners.
In a large mixing bowl, beat the butter and sugar together until light and creamy. Add the eggs, mashed bananas and vanilla and mix until combined.
Add about half of the flour, plus the baking powder, baking solda, salt and cinnamon, and mix until just combined. Add the buttermilk and mix again. Add the remaining flour and mix until the batter is smooth and fully incorporated, scraping down the sides of the bowl as needed.
Divide the batter evenly between the cupcake liners. Bake until the cupcakes are lightly golden and a toothpick inserted into the center comes out clean. Let the cupcakes cool completely before filling and frosting.
Once the cupcakes are cool, use a cupcake corer (or small knife) to remove the center of each cupcake. Fill each cupcake with banana pudding (It helps to put the pudding in a piping bag).
To make the frosting, beat the butter, powdered sugar, vanilla, and milk or cream together until a smooth frosting forms. Add more milk or cream, a small amount at a time, if needed.
Transfer the frosting to a piping bag fitted with a large star tip (I like using a Wilton 1M tip). Pipe the frosting onto each cupcake, then sprinkle with crushed vanilla wafers and decorate each cupcake with a whole vanilla wafer.
Store in the refrigerator to keep the pudding filling fresh.