Make caramel: In a pan, combine raw sugar, vanilla, and butter to make a quick caramel. Pour the caramel into a Pullman loaf pan.
Prepare bananas for caramelization: Cut yellow firm bananas lengthwise and arrange them tightly sideways on top of the caramel in the pan.
Bake caramelized bananas: Bake the pan at 330°F (160°C) for 20 minutes. Let cool completely and refrigerate.
Toast nuts: Lightly toast crushed walnuts and pistachios and set aside.
Make banana puree mixture: Blend thawed ripe bananas, banana scraps, soft dried bananas, sugar, and a splash of dark rum until smooth.
Cream butter and sugar: Cream very soft (not melted) butter with sugar until light and fluffy to create air pockets.
Add eggs and dry ingredients: Add the first egg and beat on high speed until light and fluffy. Then add a quarter of the sifted dry powders (flour, baking soda, baking powder, cocoa powder). Add the remaining eggs and mix until combined.
Combine banana puree and remaining dry powders: Incorporate the banana puree mixture and the remaining sifted powders into the batter.
Add nuts and chocolate: Fold in the toasted nuts and couverture grade chocolate discs until evenly distributed.
Prepare pan and bake: Generously grease the loaf pan and line with greased parchment paper. Pour the batter into the pan, cover with the lid, and bake at 330°F (160°C) for 1 hour and 10 minutes.
Cool and serve: Let the bread cool completely before removing from the pan. Refrigerate if desired.