My cream pie fillings are very inconsistent when making meringue pies. I've read that over stirring cornstarch thickened mixtures can cause them to break down when cooled. I've also read that over heating them can cause them to break down. My chocolate meringue pie recipe states bringing the mixture to a boil and then cooking for two additional minutes. Then I temper the eggs with the mixture, add them to the remaining mixture and bring to a boil for an additional two minutes. I try to stir gently but that equals 4 minutes of boiling the mixture! And THEN after the meringue is applied, it goes into the oven for an additional ten minutes. My recipe states to use either cornstarch or flour. Could those times stated be alright if using flour but too long for using cornstarch? I'm just trying to figure out a way that I'm not nervous every time I cut a cream pie! I also ALWAYS allow the pie to completely cool before cutting.