helpspinch casserole?

I found a recipe for the casserole, tasted OK, but should have been better. It called for 8oz mild cheddar, 8oz brick cheese, large carton cottage cheese, 2 pkgs spinach, water pressed out, 6 eggs and dash of garlic powder. Did all that but found had no brick cheese so subbed mozzarella. Said to bake til brown on top. Did that, but there were big clumps of cheese, hardish like large marbles! Where did I go wrong, or is it the recipe? (or me). Anyone have a similar recipe so I can make for Christmas???