People shouldn’t encourage OP to put laxatives in any future cakes (no matter how much someone deserves it!) because you can get into a lot of trouble for it - or make someone seriously ill.
I used to work nights as a support worker doing 12 hour shifts and spent a lot of money, time and effort cooking proper meals to take with me.
A few of the staff warned me they would gain weight on nights by eating pot noodles, junk food and take aways for convenience so I also made sure I had a few healthy snacks in case my break was very late or cut short.
One woman started doing the same shifts and I noticed my food was partly eaten (which is gross as it seemed to be eaten with a fork straight from the tub) or just taken completely. I could hide snacks but meals needed keeping in the fridge and she would still sometimes hunt out my snacks and eat them.
I approached her and said I knew it was her as it only happened after she started, she admitted it and said it didn’t seem fair that I had nice meals to eat when she didn’t! (She denied taking the snacks but it was definitely her).
I told her to just make her own and she said she didn’t have time because she had children unlike me.
I said that wasn’t my problem and that she was leaving me to go all night without any food because I couldn’t go out to get more and nowhere was open anyway.
She asked me if she gave me £5 a week if I would bring enough food for her too, I told her she was being ridiculous and couldn’t believe she hadn’t apologised when she’d basically been stealing from me.
She just moaned on about how it was easy for me to cook a few meals when I had more time and less responsibilities until I got angry and told her to fuck off and if she tried it again I’d put laxatives in it.
My boss called me into the office before my next shift and said that “Susan” had told him what had happened and he completely agreed with me but that Susan had said if I put laxatives in my food then she would call the police and have me arrested for spiking food I knew she might eat. He warned me I could potentially end up being accused of “administrating a noxious substance”.
Luckily he did give Susan a warning for theft as well and I’m not sure it was that or the threat of the laxatives but she stopped pinching my food and brought her own, she moaned constantly about how stressful it was to do and did everyone’s head in though.
She was also the person who took fistfuls from tins or boxes of sweets at Christmas, tried to take any home in her bag that someone had brought in for everyone and when the company gave us anything like an Easter egg, selection box or anything else edible we had to check she only took one and not them all.
Everyone was relieved when she left after a few months saying the staff all bullied her “like all her previous jobs” I’m guessing she was bullied at any future ones too…