On BA, even in F, all meals come partly cooked cold in tin foil. These are heated and then laid out per presentation instructions on a plate. On the one occassion when I was deciding between two main dishes, the very friendly crew brought out the uncooked version in tin foil of both for me to make up my mind (by the way, a Tesco ready meal looks far nicer)

Its the same on VS.

CX/SQ F crew are taught how to cook eggs in the galley for breakfast. Gulf Air has a dedicated Sky Chef for First pax but I am not sure how much cooking happens on board.