Muffin Pisang Karamel

Bahan-bahan (12 porsi)

• 1½ cups all-purpose flour (plain flour)
• 1½ tsp baking powder
• 11 oz overripe bananas ((2 medium bananas))
• ⅓ cup sugar ((for the caramel))
• 3 Tbsp water ((for the caramel))
• ¾ cup unsalted butter ((12 Tbsp; at room temperature))
• ⅔ cup sugar
• 2 large eggs (50 g w/o shell) ((at room temperature))
• ½ cup milk ((at room temperature))
• 1 tsp pure vanilla extract
• 6 tsp Nutella ((hazelnut spread; optional))