Question about cleaning cookie pans [View all]

I baked a pizza last night. Knowing some of the oil from the pesto was going to drip, I put a couple cookie sheets under the pizza pan. Sure enough, it dripped down and created a ton of smoke. The oil baked into the cookie sheets and it's almost impossible to scrub out even with Brillo pads. Is there any kind of spray available that'll do the job? Or any other solutions to clean them?