Ovens, even shiny new ones, run hot and cold all the time. Adding or subtracting cook time isn’t a reliable fix. Food baked or roasted in a too-hot or too-cool oven may not be ruined, but will likely have issues with texture, flavor, and color. That’s why, a mere three pages after I’m felled by a brain aneurysm in my memoir-with-recipes, Stir, I pause to issue a request: Please buy an oven thermometer. That “please” is an aggressive one—for the simple reason that placing a thermometer inside your oven and paying attention to what it tells you is one of the best and easiest ways to insure that your recipes will come out right.
Not convinced? Here are seven reasons why you need an oven thermometer in your life:
Ovens vary in the amount of time they take to heat up, and the beeps and indicator lights designed to tell you when your oven is ready are notorious liars. Ovens fluctuate above and below the set temperature in order to average out to your desired heat level. Our brand-new oven in our last apartment would shoot up to 100° F over the target temp before slowly settling back down to a temperature that more or less matched the dial. Slide a cake pan in there after 20 minutes, when a beep from the oven would say it was time, and I’d be starting off that batter at 425° F instead of the intended 325° F! (See number five, below, for the kind of trouble that spells.) Another 20 to 30 minutes later, my thermometer, beacon of truth, would tell me that our oven was good to go.
Okay, so this one’s obvious: black cookie bottoms, overdone pie crusts. That’s what can happen when the number on the dial and the actual temperature inside the oven are as little as 25° F off. A too-cool oven presents its own problems. I once baked challah for the family of my college boyfriend in an oven I didn’t realize ran cool. A guest at their table for the first time, I sawed through a beautiful, golden crust only to feel my knife catch in raw dough. (We broke up.)
Then there was my mother’s ill-fated plum cake. She intended to bake it at 350° F for an hour, dutifully preheated the oven, then accidentally turned it off at some unknown moment once the cake was already inside. She got her clean toothpick at the expected 60-minute mark, but only because the interior of the cake had melted—not baked—into a solid, gummy slab. Oh man, if only we’d had our oven thermometers.
You’re not interested in baking any old brownie. You want one that’s springy, or squidgy, or topped with the thinnest shiny crust, whatever the case may be. That’s why you chose this recipe, and not that one. You have a vision. So you measure your ingredients carefully (with a scale, yes? yes!), you invest in chocolate with the right percentage of cacao. Taking care with your ingredients and measurements then throwing your batter into an unchecked oven is a little like studying your soil, researching your seeds, spending all weekend planting—then swearing off your watering can and hoping for rain. Hey, it might work.
An oven thermometer is especially important when you’re baking at a very low temperature. (Meringues, for example.) Even ovens that are spot-on at higher temperatures can struggle to hit the mark at 300° F or lower. There is a recipe in my book for a plump little almond macaroon with a crisp outer crust and a chewy center. But heat the oven to 325° F instead of the intended 300° F, and you end up with flat, crackly cookies that crunch all the way through.
That tray of cookies may be done-ish, cooked through, even beginning to color. But for the toasted, toffee-like flavors we’re after and , the proper tanning, we need the chemistry to be right. Proteins must brown; sugars must caramelize. The oven must be hot enough so that they can.
Cakes baked at too low a temperature turn out heavy and squat. They will also be dry, thanks to the extra time needed to bake the cake through. Careful, though. In my experience, the temperature needs to be only 25° F too hot for a cake to rise too quickly, creating a peak at the surface and, sometimes, a crack.
Oven temperature is one of the factors that affects spread. For wide, flat, saucer-like cookies that bend before they break (I have just described my husband’s favorite oatmeal cookies), you need to bake the dough at a lower temperature. Thick, fat cookies require an oven that’s hotter by 25 to 50° F.
As you should, because an oven thermometer costs next to nothing, takes zero effort to operate, and changes everything for the better—by which I mean the considerably more delicious.
What's the kitchen tool that's changed your cooking life? Spread the good news in the comments.