This is the recipe we used. They turned out awesome. One of the sheets didn't cook quite long enough, maybe 8-9 minutes, but they turned out to be the favorite, a bit soft, almost like a cookie. The 3 sheets all were slightly different. 1 perfect, 1 a bit crisp, 1 a bit soft.
https://www.culinaryhill.com/homemade-graham-crackers/