Start with a pressure washer for sure. A lot will come off that way. Then dry kitty litter sitting for awhile, sweep it up and do some more.
I try hard to catch the grease coming out of my cookers for just this reason. Old sheets of scrap plywood or really old rubber mats or even a neutral colored shower curtain spread under the cooker would help too.
My driveway is asphalt so I just pressure wash it and figure I'll seal it before I sell the house. Mine's full of burn marks from welding and various nicks and gouges from dropping bits of metal or you name it. So it won't ever be pretty again but a nice even coat of sealer will hide a lot of it, take everything away, couple pots of flowers, shoot even the women will like it.