Preheat oven to 375 °F. Spray a 9x13-inch casserole dish with nonstick spray.
Whisk the eggs, egg white and applesauce together until the eggs are fully beaten and combined.
Whisk in the cocoa powder, sugar, vanilla extract, baking powder and salt
Stir in the milk
Stir in the oats
Stir in the chocolate chips and ½ cup of the hazelnuts
Sprinkle the remaining ¼ cup hazelnuts on top
Pop it in the oven for about 45 minutes, until a skewer or knife inserted into the center of the oatmeal comes out clean.