Brown the Butter: Melt ½ cup of salted butter in a medium saucepan over low to medium heat, stirring until golden brown and nutty, about 5–7 minutes. Remove from heat and let cool slightly.

Prepare the Batter: Whisk together cooled brown butter, 2 mashed bananas, 2 eggs, ½ cup Greek yogurt, and 1 teaspoon vanilla until smooth. In another bowl, combine 1½ cups flour, 1 cup brown sugar, ½ cup granulated sugar, 1 teaspoon baking soda, ½ teaspoon baking powder, ½ teaspoon salt, and optional ½ teaspoon cinnamon. Gradually add dry mix to wet ingredients.

Fill Cupcake Liners: Preheat oven to 350°F (175°C) and line a cupcake pan. Spoon batter into liners, filling about ⅔ full. Bake for 18-20 minutes until a toothpick comes out clean.

Cool Completely: Allow cupcakes to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Make Pudding Filling: Whisk 1 package of instant pudding mix with 2 cups of milk in a medium bowl until thick, about 2 minutes. Cover and refrigerate to set.

Prepare Buttercream: Beat ½ cup softened butter until light and airy. Gradually add 2 cups powdered sugar and 2 tablespoons heavy cream, beating until creamy.

Assemble Cupcakes: Create a hole in each cooled cupcake and fill with chilled pudding until it mounds slightly above the surface.

Frost and Top: Frost each filled cupcake with buttercream, sprinkle with crushed Nilla wafers, and optionally top with a slice of banana.

Serve and Enjoy: Cupcakes are ready to be served. Enjoy at room temperature.