Hi Sarah
I don't know about your particular model but most toaster-ovens have dreadful thermostats. They don't actually measure the temperature inside the oven space at all. They commonly either measure the temperature inside the space behind the switches and dials, or the "temperature" dial controls a cycling switch that cycles the elements on and off, higher setting equals longer on cycle, shorter off cycle. Those that measure the temperature behind the dials - engineers have calculated that when the temperature in the oven is X, the temperature behind the dials will be Y but this will be based on temperatures in your kitchen being the same as in their lab, no draughts, and assumptions about the food load in the oven. I have found them to be pretty inaccurate. You have to watch what's going on in the oven and adjust to suit. You can adjust them if they are out of whack - often you remove the knob and put a fine screwdriver down the hollow shaft to adjust the temperature. But still, if you put a lot of cold food in the oven at once, it will run cold for quite a while till the cycling element slowly catches up.
There is actually quite a bit of a black art to this. I had one toaster oven that, according to a thermometer I put in the oven, ran quite cold. I tweaked the thermostat adjustment and it ran reasonably true to temp, again pretty amazing considering it only measures the temperature of an aluminium bracket at the side of the oven, not oven temp itself. The thing is, once the thermometer said the oven was accurate, it was scorching food and cooking too fast. I suspect that toaster ovens are designed to run a bit cold, for a good reason. In a toaster oven the elements are much closer to the food than in a real oven, so the food is getting more radiant heat direct from the element, as well as convected heat from hot air in the oven. My guess is that these ovens will work best when the air temp is a bit lower than the selected temperature, to allow for radiant heat from the elements. Of course this will vary with different foods, it is all a compromise. I do use a benchtop oven regularly, and I find you have to watch what is happening and not rely on the thermostat too much.
Some newer ovens have a real measurement of oven temperature and the microprocessor switches the oven on and off to maintain your set temp but these are only more expensive, recent models AFAIK.
