Mine is:
Soak all your baking trays and grill/oven components in Biological Washing Powder and boiling hot water for a couple of hours. It lifts all the grease off with no effort at all. Then use a scourer to lift the last stubborn bits off.
Don't bother buying loads of chemical cleaners, just use stardrops and invest in an E-cloth.
Please feel free to add...