Hi, and welcome to Discuss Cooking [emoji2]
A few things you can make are meringue cookies, or topping for a pie; angel food cake; and challah, a type of bread. Challah makes great pain perdu
Welcome to DC..
No idea how many you cook for.. There are 2 of us so, I do small batch recipes..
My go to for cooking for two is Christina Lane with her Dessert for Two website.. She also has many savory recipes.
She has a section for leftover egg whites.. (also for leftover egg yolks)
https://www.dessertfortwo.com/category/egg-white-only/
Hope this is of interest..
Ross