Distribute the sugar in an even layer on a baking sheet and bake for 8 minutes. While the sugar is baking, add the egg whites to a stand mixer with the salt.
Once the sugar has been in the oven for 7 minutes, begin beating the whites on high. After a minute they should be foamy. With the mixer still running, gradually sprinkle in the warm sugar, cinnamon and vanilla. Once all of it has been added, beat on high until the meringue is cold, about 10 minutes.
Reduce the oven temperature to 200 degrees F.
Line a baking sheet with parchment. Place the crushed cookies on a plate. Using a large ice cream scoop or 2 large spoons, scoop up a big dollop of meringue and place it on the plate of cookies so that they stick to the bottom. Use a spatula to carefully transfer it to the baking sheet.
Bake until the outsides are crunchy and the insides are still slightly soft, about 2 hours. Allow them to cool completely on the baking sheet until hard, about 30 minutes.
I like separating the eggs one at a time into a separate small bowl first, in case I break a yolk. Even the tiniest bit of yolk will prevent whites from getting fluffy.