Preheat your oven to 350°F (175°C), then line a baking sheet with parchment paper. You’ll turn the oven off later, but this initial heat is crucial.

In a completely clean, dry bowl, beat the egg whites on medium speed until soft peaks form. Gradually add the sugar, one spoonful at a time, continuing to beat until the mixture is glossy and forms stiff peaks. This takes about 5–7 minutes.

Gently fold in the vanilla extract, a pinch of salt, and then your mix-ins—chocolate chips and chopped nuts if using. Be careful not to deflate the meringue.

Drop the mixture by heaping spoonfuls onto your prepared baking sheet. Leave space between each cookie as they may spread slightly.

Place the cookies in the oven and immediately turn the oven OFF. Now comes the magic—do not open the door. Leave the cookies in the oven overnight (or for at least 8 hours). They will slowly set and crisp in the gentle heat.

In the morning (or after a long wait), open the oven to find beautifully crisp, light cookies that crackle with every bite.