Every broiler is different, and it's important to know how the position of your food in the oven will affect the finished dish.
Uneven broiler heat is a fact of kitchen life; even with identical oven models, we’ve found individual quirks. But in general, most broilers tend to heat up the center and back of the oven, leaving the sides and front cool. To be sure about your oven’s heating pattern, make a "map" by lining a baking sheet with white bread and toasting it under the broiler. The different degrees of browning with provide an accurate representation of the oven's hot spots and cooler regions, so you can position food accordingly (and, if necessary, switch it partway through cooking).
HOW TO MAKE A BROILER "MAP":
1. Position the oven rack 4 inches from the broiler element and heat the broiler. Line the entire surface of a large baking sheet with a single layer of white bread slices.
2. Place the bread in the oven under the heated broiler. Cook until all of the slices have started to brown (some pieces may turn black—if the bread starts to smoke, remove the baking sheet immediately). Remove the baking sheet from the oven, being careful to make a note of its orientation.
3. Take a photo of your broiler map and keep it near your oven.