Preheat your oven to 350°F (175°C) and line an 8x8 inch baking pan with aluminum foil, leaving overhang for easy removal. Lightly spray the foil with cooking spray.

In a microwave-safe bowl, combine the white chocolate chips and unsalted butter. Heat in the microwave in 30-second intervals, stirring after each, until smooth and completely melted.

Allow the melted mixture to cool slightly, then whisk in the egg, granulated sugar, and vanilla extract until well combined.

Add the mashed banana to the bowl, mixing until fully incorporated.

Gently stir in the all-purpose flour and a pinch of salt until just combined.

Pour the batter into the prepared baking pan, using a spatula to smooth the top evenly.

Place the pan in the preheated oven and bake for 32-33 minutes, checking for doneness with a toothpick.

In a small saucepan, melt additional unsalted butter over medium heat until golden brown. Remove from heat and mix with confectioners' sugar, vanilla bean paste, and heavy cream.

Once the bars are out of the oven, pour the glaze generously over the top while still warm.

Allow the bars to cool completely in the pan before lifting them out, then slice into squares.