In a way that stimulates or arouses appetite or desire; tantalizingly.
From appetizing (present participle of appetize) plus the adverbial suffix -ly. The chain goes: appetite → appetize → appetizing → appetizingly, with each suffix building on the previous form.
When a food commercial shows a pizza with cheese stretching and steam rising, they're doing it 'appetizingly'—filming in a way designed to make you crave it. Food photography is basically the art of being appetizingly deceptive!
Complete word intelligence in one call. Free tier — 50 lookups/day.