I recently developed a recipe for a chocolate sheet cake shrouded in brown butter frosting. Not to put too fine a point on it, but the test kitchen went wild. Chris Morocco, test kitchen director and side eyer of most things sweet, deigned to eat an entire slice. Former senior food editor Christina Chaey swaddled squares in foil and biked them over the bridge to Brooklyn for an after-dinner treat. Slack messages cried “run.”
What was it about this cake that made it so special? Sure, the cake itself was really good––moist, fluffy, and easy to make. But it was the brown butter frosting talking the loudest. Intensely toasty and almost caramely, it stopped everyone in their tracks. “How?” they asked. “Milk powder,” I whispered, shaking a bag in their face. Allow me to explain.
Brown Butter Is Better Butter
Butter is pretty much all fat, plus a little water and some sugar and protein poetically lumped together as milk solids. When you brown butter, by cooking it for a length of time, the milk solids toast and darken. It’s these toasted milk solids (not the fat itself) that give brown butter its nutty taste and make it a stellar addition to rice cakes, noodles, and cookies.
But have you ever baked something brown butter–flavored and it’s barely noticeable, buried beneath sugar and dairy and whatever else is going on? With milk solids clocking in at 2% or less, this is inevitable. We want a lot of browned milk solids, but we don’t want to melt and separate pounds and pounds of butter to get there. If you want brown butter to be the mayor of Flavor Town, the main character of the story, you’ve got to maximize those milk solids.
Milk Powder: the Miracle Agent
Enter from stage right: nonfat dry milk powder. Milk is mostly water, with some fat and milk solids (same building blocks as butter, just different ratios). Remove the water and fat and you get nonfat milk powder—what is essentially pure milk solids. The very same milk solids that play a starring role in brown butter. Which means all you have to do is add a scoop of milk powder to melting butter, and you’ll go from brown butter to brown-est butter.
I first learned of this technique many years ago from the blog Ideas in Food, a dizzying treasure trove of ideas from Aki Kamozawa and Alex Talbot. There, they chronicle toasting milk solids in a pressure cooker to get a fine, dry powder that you can toss wherever you want the flavor of brown butter.
Butter-Toasted Milk Powder = Big Brown Butter Energy
My go-to method is to simply toast milk powder in a pool of butter. Per stick of butter, use as little as 2 Tbsp. milk powder (as in these Peanut Butter Rice Krispie Treats) or as much as 1/4 cup milk powder (like that chocolate cake). Melt the butter, add the milk powder, and cook, stirring constantly, until deep golden brown. Push the browning as far as you dare, stopping just short of espresso brown. The deeper the color, the bolder the flavor.