Love that question, Susanna! The lemon meringue pie recipe below has cornstarch in both the filling and the meringue, to serve as both a thickener as well as a stabilizer in the event the egg proteins get too hot. But how exactly does that work? Well you may remember me talking about “the clenching fist” in the past, a metaphor that describes what happens when intertwined egg proteins get too hot and curl up…squeezing out water as they tighten into little clumps. That’s curdling. It can’t ultimately be prevented but it can be forestalled by the addition of starch to the mixture. Starch molecules do a couple of things in a custard. First, they absorb some of the heat energy, thus protecting the more delicate proteins. Second, they get in between the proteins, making it harder for them to curl up tightly. Eventually they will of course, if the heat remains too high for too long, but starch can perform amazing feats as an insulator and curdle inhibitor. Thanks, Susanna!