i need help with my burning bottoms! the bottoms of my cookies, my muffins, my chicken cutlets etc. all seem to get crusty and burn. i just moved so i am dealing with an older oven which is gas. i bought an oven thermometer so i can check the temp. when i bake, but i haven't had a chance to use it. besides the temp., can anyone offer some tips to a not-so-novice cook? thanks!