I heard that you’re dying to talk about meringue. Wonderful, me too. I love working with meringue. When I’m helping with production at the Bakeshop, I selfishly take all the projects that involve meringue (buttercream, chiffon cake) and put them on my list. My staff loves it
Meringue – which in its simplest form, is egg whites beaten with sugar – progresses incrementally from foamy, to soft peak, medium peak, and then stiff peak. After that, it progresses to overbeaten and hard to use, at which point you might be tempted to swear off ever making it again. An overbeaten meringue is often called “marshmallow-y” because folding it into something else often results in stubborn chunks of meringue that refuse to break up and look like marshmallows.
But let’s back up. A common misconception is that a stiffer meringue will be more effective at lightening your batters because it seems “stronger” — it’s not. A meringue is most voluminous and flexible at soft peak (i.e. a peak that falls over forming a hook shape). When a meringue is being used to lighten or leaven, we want to use the meringue when it’s at the highest possible volume while also being stiff enough to be easily blended with a thicker batter or folded into dry ingredients. For an Angel Food Cake, this is medium peak (i.e. a peak that still leans over, but doesn’t fully form a hook shape).
There’s certainly a lot more to be said about meringues: proteins, acid, copper bowls, etc. If you want to fall down this rabbit hole, Harold McGee’s On Food and Cooking is a great source for that information.
However, to make Angel Food Cake, or a basic meringue for baking, not all of that information is necessary. Follow the recipe: use room temperature egg whites, don’t skip the cream of tartar, add the sugar slowly — and most importantly, don’t overbeat. Once the meringue starts to look smooth and glossy, check it as often as you need by pulling out the whisk, flipping it over and looking at the peak. And remember: going past soft or medium peak will not increase the volume or stability of your final product. So don’t do it. You’ve got this.