• Gather all the ingredients.
  
• Preheat the oven to 350ºF (180ºC). For a convection oven, reduce cooking temperature by 25ºF (15ºC). Lightly spray the muffin tin with nonstick cooking spray or line with cupcake liners.
• Sift 1½ cups all-purpose flour (plain flour) and 1½ tsp baking powder. Peel 11 oz overripe bananas and cut into thin slices.
  
• To make the caramel, cook ⅓ cup sugar and 3 Tbsp water over medium heat in a small saucepan. Gently tilt the pan off the heat to distribute the color evenly as the sugar caramelizes.
  
• When the mixture turns a nice amber color, immediately add the sliced bananas and coat them with the caramel. Turn off the heat.
  
• In the bowl of an electric mixer, beat ¾ cup unsalted butter (at room temperature) on medium-high speed until soft. Then, add ⅔ cup sugar and mix until creamy and fluffy.
  
• Whisk 2 large eggs (50 g each w/o shell) in a bowl, stir into the batter, and blend well.
  
• Add half of the flour mixture to the batter and mix well. Then, stir in half of the ½ cup milk. Add the rest of the flour and mix, and finally stir in the rest of milk. Mix well to combine.
  
• Add 1 tsp pure vanilla extract and fold in the caramelized bananas just until combined.
  

To Bake

• Spoon the batter into the muffin tin about three-quarters full. If you‘d like, top each muffin with ½ tsp Nutella (for a total of 6 tsp Nutella) and use a skewer or chopstick to swirl it into the batter.
  
• Bake the muffins at 350ºF (180ºC) for about 25 minutes, or until a skewer inserted in the center comes out clean. Serve warm or let cool completely for storage.
  

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for up to 4–5 days and in the freezer for a month.