In a shallow bowl, whisk together the egg, eggnog, cinnamon, and vanilla.
Cut a pocket in each slice of bread. Don't cut all the way through the bread, just create a pocket. Carefully put a large scoop of Nutella in the pocket and gently close the edges, somewhat sealing the Nutella inside.
Heat a saucepan over medium high heat. Add a small piece of butter to the pan. Dip each slice of bread in the egg mixture, so it is lightly coated, and add to the pan.
Cook until golden brown on both sides and enjoy!
