I up the comfort factor by tossing the slow-roasted onions in a homemade truffle lard. The truffle lard keeps for up to 3 months in the fridge. I like to add it to all kinds of vegetables for roasting, use it to rub through pastry for savoury pies or simply smeared over warm toast.
The onions are served on a bed of truffle polenta, made with milk (instead of stock) as the lactic acid helps unlock the truffle flavour. Layering the truffle flavours magnifies its depth.