reheat oven to 350F/170C. Using a stand mixer, combine all dry ingredients (flour, sugar, baking powder, baking soda, and salt) and mix. Turn mixer to low and add eggs, vanilla, oil, water and buttermilk. Mix until combined. Line muffin/cupcake pan with liners and place a tablespoon of batter in the bottom of the well. Place a Ferraro Rocher in the center, and top with another tablespoon of batter. Repeat until all wells are filled and bake for 20 minutes. Allow to cool completely before frosting.
In bowl of a stand mixer, cream butter until light and fluffy. Add icing sugar and combine. Add vanilla, Nutella and cream one tablespoon at a time until desired consistency is reached.
*Once cupcakes are cool, pipe buttercream onto cupcake and coat sides with hazelnuts.
*Pipe additional Nutella on top of buttercream to add colour.