Sob... some of us are born in August.... sob....
lisalisa.... there is someone that runs cooking events / courses from their home in the Suburb. Was featured in Suburb News I think within the last month or so. Could possibly find name as I am on a mailing list for the area.
Would think that if you aren't fazed by a crowd at your place, the cooking courses /events at home might be more profitable / easier... you keep an exercise book by the phone to log names / numbers / age / bookings. A course could be structured over 4 (or more) weekends or you could simply do a fun project suitable for different ages on each Sunday: 1st Sunday every month is under 5s. 2nd Sunday is 5 -9s, 3rd Sunday is 9+, 4th Sunday is holiday !
Remember if you do kids parties you will need to cook in different kitchens, dealing with possibly faulty / weird cookers, you'll need to add a pile of ingredients to a shopping trip or do one specially... you'll have the time to set up, you'll have the time to bake / teach, you'll have the time to clean up... (ie. it might actually take more time than you realise).
With the course: you invest in your prep / advertising, then you sit back (as if) and wait for 5 - 15 bookings...
I might be tempted to charge for food against the receipt separately, and parent can keep any remaining ingredients (which they might not want )... that way people feel they're not getting ripped off on the eggs etc. or they could choose to shop themselves from their favourite supermarket. Also means that if someone wants you to cook something especially expensive (or especially cheap) you can accommodate that without affecting profit which is your hourly / daily / event rate, IYSWIM.
HTH