Dear Home-Ec 101,
My oven burns pizza and biscuits on the bottom and the top is under-done.
Pastry Proselyte in Provence
There are many factors that could be at play inside your oven, it’s going to take some detective work on your part to get to the [burnt] bottom of your mystery.
Here are the tools you’ll need to ensure you need to fine tune your technique or appliance, rather than repair your oven:
- An oven thermometer
- a baking sheet -actually a baker’s half-sheet, if your home oven isn’t a professional model
- oven mitts or a dishtowel, because burnt fingers aren’t fun
- cheap, white bread -no matter who you are or what you normally eat, just grab a loaf of the crappiest, cheapest white bread you can find at the grocery store. You can give it to the pigeons when you are done, this is for SCIENCE, people, not personal consumption.
- Your brain -not optional
- a digital camera OR a piece of paper and a pencil
This project is going to take a little bit of time, but it’ll be worth it in reduced annoyance alone.
First we need to see if your oven is even getting to the right temperature or if the appliance needs to be calibrated.
Make sure one of the racks is in the middle position, hang the oven thermometer from the rack, close the oven door, and turn on the oven. If your oven has an automatic pre-heat it to 350°F setting use that and if not, set it to pre-heat to 350°F. If the oven is electric, open the door and observe the heating elements, in the pre-heat phase of baking, both the top and bottom elements should be heating. Are they? Great.
Close the door.
No? Only the bottom element is working? You’ve found the cause of your problem. Home owners, replace the top element, renters have the top element replaced by your landlord. Bookmark this page and come back once both elements are working.
If your oven is gas, the heat comes from the bottom, regardless. Set the oven to pre-heat to 350°F and chill for a bit. Heh.
Once the oven has pre-heated, set the temperature for 350°F. Give the oven five more minutes. Why? Because this lets the whole oven come to temperature and not just the area nearest the thermostat. Now, look at your oven thermometer. Does it read 350°F? Yes? Fantastic, skip ahead.
No, the oven thermometer does not read 350°F. This can be for a couple of reasons, the thermostat may be broken or it may simply need to be calibrated. (That’s an upcoming article, in the interim pay attention to the difference between the set temperature and the recorded temperature. Leave a post-it note or other reminder somewhere you can see, but not set on fire. It should say let you know how far off the oven is. You may want to also check the difference at 400°F as it may not be as simple as 10 degrees low.)
The elements both work and the temperature is right, but things still aren’t happy.
Pre-heat the oven to 350°F.
Now you get to solve the mystery of the white bread.
I want you to think about your oven, it’s not a magic box. Cooking food is a balance of applying enough heat to cook the inside of food in a reasonable amount of time and balancing that with the need to not burn the outside before the interior is cooked. This is true regardless of the cooking method. When baking or roasting, the temperature of the air in the oven is responsible for the majority of the heat transfer (indirect heating). However, the baking sheet (or muffin tin or pan) gets heated by the air, too. Metal is a great conductor of heat, in fact it is far better at heat transference than air. Once the pan reaches the temperature of the oven, it also cooks your food through direct heating. This is why the bottom of your food gets done before the top (and quite possibly the middle). Some of this you can control by using the upper rack position -this slows the heating of your baking sheet and decreases the distance to the top of the oven which reflects heat back onto your food.
Get your baking sheet and cover it in a single layer of the white bread. Get your digital camera or that pencil and paper. Ready? Good. Place the baking sheet in your oven, close the door, and get comfortable in front of the oven. Pretend you’re Jane Goodall and get ready to take notes on the behaviour of your appliance.
Watch as the bread begins to brown, you need to wait until all areas of the top of the bread are at least tan and then remove the baking sheet from the oven.
Now take a picture of the bread (you may want to include a sticky note in the frame to show you which way the baking sheet is oriented) or sketch it on your paper and pay particular attention to what areas of the bread are darkest. You are creating a heat zone map of your oven, just like people, ovens are special little snowflakes and have quirks. Once you know this, you can take advantage of their hot and cool spots depending on your baking needs.
If you took a picture, you’ll need to get it printed. If you drew a picture, tape it to the inside of the nearest cabinet, but make sure it is oriented in a way that makes sense to you. You don’t want to have to remember you need to turn the baking sheet around when you’re cooking for company.
Now turn each piece of bread over, do a horizontal flip, not a vertical one, and again either take a picture or make a sketch. Is the bread significantly darker on the bottom? Then you know next time to move the rack a bit higher. Repeat and see what happens. When you find the rack position that browns the top of your toast without burning the bottom, note it and use it the next time you bake.
I’d like to acknowledge Nathalie Dupree for sharing this technique at one of her presentations. I highly recommend getting to know your appliance as a way to prevent frustration and burnt food.
Submit your questions to firstname.lastname@example.org.