Have read this with interest as the Zebra Kittens - well, blonde!kitten, mostly - have started trying to nab human!food.
They seem genuinely confused as to what can possibly have upset us though: they know I am cross, they know I am saying no, they know an attempt to swipe food from my bowl/plate will result in their ejection from the room whilst I eat. Blonde!kitten keeps doing it, though. Black!kitten might attempt a quick snifflet at what I am eating, but no more. (They are both crazy about breakfast cereal though. I came downstairs one morning to discover a scene of devastation in the dining room where they had slaughtered the entire massed collection of cereal & porridge.) Their food has to be kept shut away from them completely now too: they'd [try to] break into packets & it is not unknown for them to empty out the kitchen bin to be sure there's not anything in there for them. They think my bedroom bins are cornucopiae of delight, too.
Blonde!kitten is also prone to accidental!clawing & has no idea what it is that has provoked the strange sound from me much less why I have stopped him from snuggling with me.
Neither of them recognise hissing as a deterrent. Blonde!kitten gives away having something he shouldn't by growling & humping about the place with it.
The only time they know clapping means "no!" is if they're getting too rough with each other: they jump apart & look terribly guilty. Blonde!kitten will also come down off the curtain he has just leapt up & attempt to pretend I had obviously been seeing things.
Pair of them are awful about kitchen surfaces. They had to be kept in the kitchen when Home Alone for quite a while & their greatest delight is tap-dancing across the worktops. No food gets left out or anything, but they love looking out of the window, which is only reachable via worktops. Suspect part of problem may be I remove them instantly with a firm "no!" while my b[r]other lets them bop about until they venture near the stove at which point he gets all flaily & they (understandably) get confused. sigh
Suspect they were both massively influenced by their life before coming to life chez Zebra: food appeared at completely random intervals & had to be fought over & Mummy Cat (probably resigned to losing her umpteenth litter of kittens) didn't teach them all she could have. (Though some of the toileting issues might be down to them learning in Less Than Ideal conditions, too...)
Huff
It does sound as though she's in Mad Scavenge Mode, prolly brought on by the change in circs. If she's lived with humans before & not had the best time of things she might not be too confident she'll REALLY keep getting fed etc. Hope she settles down soon. And that your cakes will be safe in future...