Sweet potatoes, originally introduced from Spain and the Canary Islands, were in common use in England long before the so-called Virginia potato.
On Naxos they were a staple form of winter food, roasted in the ashes of a wood fire or in the bread oven as it cooled. In places where poverty restricts the purchase of sugar, they are prized, as is the winter pumpkin, both being rich in sugar.
One can of course bake them like parsnips in the oven, or take a hint from Parkinson and, having baked them, reduce them to a purée and serve with beef marrow and powdered cinnamon. In Falstaf’s time they were roasted, then steeped in sack (which derives from vin seck, dry wine, i e dry sherry, imported also from Spain) and sugar.