Eureka! I’ve found the magic elixir for impossibly tender cakes. It’s real honest-to-goodness buttermilk, and the only place I’ve found it is in New England, made by the same family in Old Orchard, Maine, who make Kate’s Butter.
I can just hear all you bakers out there yawning and saying, that’s nothing new, we’ve known about buttermilk for years. The truth is, the commercial buttermilk you’ve been buying in the supermarket isn’t buttermilk. It’s cultured milk—usually skim milk—and often thickeners are added to give it extra body.
Real buttermilk is what’s left after cream has been churned into butter. According to Dr. Robert Bradley, Emeritus Professor of Food Science at the University of Wisconsin, “When you churn cream, the flat globules in the cream collide and the membranes surrounding the globules get stripped off. Those membranes go into the buttermilk, and they contain phospholipids that provide the emulsion stability that you need to make a good cake.”
Real buttermilk made a spectacular birthday cake for Gourmet Live when I was developing the recipe in New Hampshire. But what about all of you, who can’t buy true buttermilk? What should you use? Back in New York City, I retested the recipe with other cultured dairy products. Whole-milk yogurt—not cultured skim milk—came the closest to replicating the results I got with real buttermilk. Of course, you could take inspiration from your ancestors and make your own butter and buttermilk, enough for the cake with some leftover for pancakes, muffins, or scones. I can’t wait to try that myself. Let me know how yours turns out!