Serving size per cookie- can I make them smaller to yield more cookies per batch

Estela Lam -
A few comments.
Cookies and baked good by Payard are great!
The egg whites here, as in a meringue, are providing most of the volume.
You don’t have to throw out (unused) egg yolks. They can be used in a few days for sauces, omelettes, pancakes etc. or frozen for later use.
Yes, you could try smaller portioned cookies with a shorter baking time. Just watch them carefully the first time you make them to get them cooked but not overdone