How to clean gross cookie/baking sheets

My baking sheets look pretty terrible after Christmas. So I went online to see what the YouTuberverse recommends for a home clean. Apparently we can use anything from ammonia or white vinegar with baking soda and some soaking to loosen the baked-in grime. Then Brillo pads to scrape the loosened grime away, but there’s no easy fix. They all seem to involve more elbow grease than a tray deserves!

However, after looking at half a dozen videos, I decided that this guy came out with the cleanest tray. Have a look.