You could try putting an ad on Homeservice24:
https://homeservice24.ch/de
As you will see if you browse the listings, there seems to be a higher concentration of folks offering cleaning services rather than household assistant and personal cook services. But nonetheless this is a widely used platform Swiss-wide, so chances are you might pique some interest for your position.
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There are also several concierge type companies offering tailor-made household assistant solutions. You will pay a premium for these, especially for a personal chef. I'm not going to link any of these, as one or two have a reptuation of targeting 'newly arrived UHNW' who don't yet know the Swiss market without providing the level of service one expects for the prices demanded. But if you search for 'concierge service' or 'butler service' you will find them.
I'm sure there must be some very good companies out there, but you need to do your due diligence if you go this route, look behind the glossy marketing - and make sure the person you hire to do the work is actually getting a fair portion of the price you are paying to the company.
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FYI, if you want to reduce the administrative burden of hiring household help, there is a service, Quitt.ch (
https://quitt.ch ), that pretty much does that for you. Also the '24' franchise of platforms - the Homeservice24 linked above is one of them - now offers something similar.