In a bowl, whisk the eggs and sugar together. Add the butter, milk and orange zest. Mix well, and then add the flour and salt. Stir until you get a very smooth batter.
Heat a frying pan over medium heat, and brush with oil. Pour in a ladleful of batter and rotate pan so that it covers the entire bottom of the skillet. When the edges are golden, flip crepe to brown the other side. Spread with Nutella and sprinkle a little powdered sugar before serving.