Preheat your oven to 350°F (175°C) and line a muffin pan with paper liners or grease it.

In a mixing bowl, cream the softened butter with granulated sugar until light and fluffy for 1-2 minutes.

Add eggs, vanilla extract, milk, and mashed bananas; blend until smooth without lumps.

In a separate bowl, whisk together flour, baking powder, baking soda, and salt. Fold into the wet mixture until just combined.

Spoon batter into muffin cups about 3/4 full and add a teaspoon of Nutella on each top. Swirl lightly.

Bake for 15-17 minutes until golden brown and a toothpick comes out clean.

Cool in the pan for 10 minutes then transfer to a wire rack to cool completely before serving.