Samantha Douglass asked on Facebook:
“I love the flavor that browned butter gives to…well, nearly everything. Since butter also has a functional purpose in recipes, I wonder about using it in baked goods. Does butter lose its shortening power once browned? Ought one substitute it only for a portion of a recipe’s butter or is it possible to substitute browned butter for all the unbrowned? Does browned butter solidify sufficiently to use in recipes requiring solid butter?”
You’d think butter couldn’t be improved upon, until you discover brown butter: It’s nutty, it’s toasty, and it makes anything taste better. So why not bake with it? No good reason: If you have a recipe that doesn’t include it, but one you think would be improved (or just nicely varied) with those deeper flavors, there are a few things to keep in mind.
First consider butter’s purpose in the recipe: Look at the temperature of the butter called for, and remember that soft butter is best for incorporating sugar, cold butter creates flaky pastry, and melted butter makes for moist, chewy baked goods.
Obviously brown butter can be swapped for all or a portion of melted butter in any recipe. It can also be subbed for all or some oil in moist baked goods like quick breads.
“Forgiving” baked goods like cookies, bars, quick breads, muffins, pancakes, and waffles should all be fine with brown butter. Those are the recipes that call for either liquid fat, or creaming—really, incorporating sugar—which brown butter can do. It’s pastry and fussy cake batters (“unforgiving” baked goods) that require more caution and I would suggest researching other similar recipes that call for brown butter to get a better sense of how much to use.
Since I’ve never made a brown butter piecrust, I can’t attest to its flakiness. I do have a recipe in How to Bake Everything for Brown Butter Brioche that re-solidifies the butter after browning. That’s one way to get the best of both worlds, and a technique worth experimenting with if you can’t get enough of that toasted taste.
In case you’re wondering, to brown butter: Gently heat unsalted butter until it melts and the milk solids become toasted. The darker the color the deeper the flavors; the butter will change quickly and get darker as it cooks. So you’ve got to watch it constantly and remove the pan from the heat the moment before it’s the shade you want.