In a small saucepan, begin cooking the sugar and cider on medium high. Keep a cooking thermometer nearby so you can frequently check the temperature, especially as it starts to boil.
Meanwhile, begin whipping the egg whites in a stand mixer with a whisk attachment on medium high speed. You can use a hand mixer, but I would recommend using a stand one since it can take a while to get the eggs to the right consistency.
When the sugar reaches 250 degrees remove it from heat and pour into a glass jar or other heat proof container while you wait for the egg whites to be ready.
When egg whites are starting to form soft peaks (just starting to firm up), pour in the sugar mixture slowly as the mixer continues to beat on medium high speed.
Add cinnamon, salt, and vanilla.
Continue whipping until you have stiff peaks. This means that when you lift the whisk or stir it with a spoon, it should hold its shape firmly.
Now you have a couple options! You can Immediately pile it onto the top of a pie and place it into the fridge to set. You can also make it into meringue cookies. Put the meringue into a bag and pipe into small round discs. Place into a 200 degree oven for one hour, then turn the oven off but leave the cookies inside until they’re thoroughly hard and dried. You may need to leave them overnight to achieve this.