American family, 3 children, I think. Nanny makes fantastic bread-and-butter pudding and the children enter her recipe in a cookery competition. She gets through to the final cook-offs, but the parents are abroad. So she arranges for someone to come and look after the LOs. But the someone is a ghastly woman, who likes things like okra instead of hotdogs. The youngest child takes matters into his own hands by ordering a voodoo kit from the back of a magazine. He makes a wax dummy of the woman, and makes it snow in the town - but nowhere else.
I can't remember the rest! Does anyone recognise it?