Combine the flour, sugar, baking powder and salt in a bowl. In a separate bowl, whisk the egg yolks, then add the milk and butter. Add the flour mixture and whisk until well combined, but still lumpy.

In a separate bowl, beat the egg whites with an electric mixer until stiff peaks form. Add 1/3 of the egg whites to the batter and gently fold to combine. Add the remaining egg whites and gently fold until just combined.

Spray an ebelskiver pan with cooking spray and place on a stove set to medium heat. Once the pan is warm, spoon about 2 tbsp of batter into each well. Dollop about 1 tsp of Nutella into the center of each well – placing the Nutella in a piping bag makes this MUCH easier! Spoon enough batter on top to seal the pancakes closed.

Once the surface begins to bubble, flip over the pancakes using two skewers, so that the cooked side is facing up. Cook until the bottom turns golden brown.

Transfer the pancakes to a plate and enjoy!