When shopping for kitchen appliances before an old renovation, the saleswoman touted the benefit of convection in an electric oven. To ensure even cooking when cooking two sheet pans of cookies, recipes recommend swapping the upper and lower racks and rotating the pans midway through cooking. Not necessary with this oven, the saleswoman noted; just switch on convection and all the cookies reach equal perfection.
Using my M&M Cookies recipe, I decided to test put the theory to the test. Though I normally cook only one tray at a time, I still rotate it 180° midway through. I cooked one batch the usual way at 375 °F for 10 minutes. For the next batch, I decreased the temperature to 350 °F (a 25° F decrease is typically recommended when switching to convection). I typically rest my cookies on the sheet pan for about 3 minutes after they come out of the oven, to finish baking without drying out.
The non-convection version came out exactly as expected, with a slightly crispy crust, but a soft interior, just like the family demands.
The convection batch was a different story. The cookies spread considerably less and had an over-toasted crust. Even at the lower temperature, the hot air caused the outside to set and excessively brown before the insides had properly cooked.
It’s possible that an even lower temperature would have helped, but my experience is that convection is best reserved for foods where the interior would overcook before the outside reached it’s appropriate level of crustiness, and where a drying effect is particularly desirable. This is great for some meat dishes or for oven fries. For cookies, however, I have yet to see an improvement.