Preheat your oven to 350° F. Then, cover a baking pan with foil and grease it.
Use a large mixing bowl to beat the egg whites until foamy. Use either a whisk or hand mixer at medium-speed. A stand mixer works well too.
Continue to beat the egg whites and gradually add the sugar. Keep beating utnil you stiff peaks form. Stir in the vanilla and salt and mix well. Then, fold in the the chocolate chips and optional nuts, using a spatula.
Use a teaspoon to drop the dough onto the prepared baking sheet. Place the pan in the oven and turn it off. Leave the cookies in the oven overnight (do not open the door) for about 10 hours.
Baking Tips for Egg White Cookies
Use a spring-loaded ice cream scoop to portion out the dough. This will make these overnight cookies uniform in size.
Be sure not to open the oven door once you place the cookies inside. It is important that no heat escapes, to allow these egg white cookies to bake.