Sprinkle the pan with baking soda to form an even layer. Pour some hydrogen peroxide into a spray bottle (or screw a spray top directly onto the peroxide bottle) and use it to spray enough hydrogen peroxide to wet the baking soda.Let the ingredients sit on the baking sheet for about two hours. After letting it sit, use a gloved hand or a sponge to scrub the baking sheet, and the baking soda mixture should quickly darken from all the loosened grease.Rinse the baking soda mixture off of the baking sheet and check your progress on the stains. If it’s not quite clean yet, repeat the cleaning process again to remove the remaining grime.Sprinkle cream of tartar evenly across the surface of the baking sheet. Pour some white vinegar into a spray bottle, then add it to the cream of tartar by spraying it with enough vinegar to wet it.Allow the tartar mixture to dry on the baking sheet for at least eight hours (overnight is perfect.) After the wait, use a bit of hot water and a sponge or scrub brush to scrub the baking sheet thoroughly.After giving it some elbow grease, rinse the baking sheet with warm water and check your progress, then repeat the process if necessary.And finally, there’s good old Bar Keepers Friend. Available as both a scouring powder and a cleaning paste, Bar Keepers Friend often succeeds at removing messes from metal where other cleaners fall short!After donning a pair of cleaning gloves, simply apply a bit of Bar Keepers Friend to a grimy sheet pan and scrub with a sponge or brush. According to the directions on the container, you’re not supposed to leave this cleaner on a surface for more than a few minutes. The best way I’ve found is to clean smaller sections of the baking sheet one at a time, rinsing each section thoroughly with warm water after scrubbing.Continue scrubbing your way around the baking sheet until the food stains are gone. Easy!