Preheat your oven to 350°F (175°C). Grease a 4x8-inch loaf pan generously with butter.
In a large mixing bowl, mash the peeled bananas until completely smooth. Stir in the melted butter until fully combined.
Lightly beat the egg in a small separate bowl.
Add the egg and the remaining ingredients to the banana mixture, mixing for about 1 minute after each addition.
Gently fold the walnuts into the batter with a spatula.
Pour the batter into the prepared loaf pan and bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean.
Remove from the oven and let the loaf cool in the pan before transferring to a wire rack. Allow it to cool completely before serving.
Caramel Topping
In a small saucepan over medium heat, combine sugar and salt, then add water to cover.
Bring the mixture to a simmer, stirring occasionally until the sugar is fully dissolved (about 5 minutes).
Increase the heat to medium-high and cook without stirring until the mixture turns a deep golden color. If using a candy thermometer, it should reach 350°F (175°C).
Once the caramel is a rich copper color, remove from heat and carefully stir in the cream and butter until smooth.
Let the caramel cool slightly in the pan, then transfer it to a heatproof container.
Spread the cooled caramel evenly over the banana bread using a spoon or spatula.
Garnish with dehydrated banana slices and walnuts for decoration.