Fill
donut pans 1/2 way using a teaspoon (about 1 1/2 teaspoons of batter per donut hole). Using 1/3 cup pre-melted Nutella, pour 1 teaspoon Nutella per donut over the batter in the pans. Carefully cover each donut with remaining batter, using your fingertips if you need too, to make sure there is a secure 'lid' over the tops.