My (among other students) biggest issue with making the flan is over cooking. Flan is suppose to be a custard. When you over cook it the batter will start to cross over to the texture of a cake, with air holes etc. When checking for doneness, Chef (my instructor), said the custard should jiggle like jello not wave like water. I over cooked my maybe by 10 minutes so I would suggest to start checking around the 20-30 minute mark. I would also suggest using Grand Mariner instead of OJ, yumm. Discloser: Chef is from West Texas, born and raised. He is married to a Mexican woman and says this recipe is not the best flan recipe out there. Again I am just sharing my recipes from culinary school and maybe one day when I find the perfect flan recipe I'll add it.