Here is another difficult expression from "Harry Potter".

I may be as woefully wrong as Humphrey Belcher who believed the time was ripe for a cheese cauldron.

What does the cheese cauldron mean here? Is it about cheese-making, or is it a kind of snack, or something?

Thanx in advance.
Cauldrons are pots normally used for brewing up magical potions. Without having read the book, I presume that Humphrey likes his food, and wanted to use his cauldron to melt cheese for fondue. Not the thing to use one's cauldron for, if one is a serious apprentice wizard!

The idea was to create a cauldron, that one can use to brew potions in, made of cheese.

However, as many potions are required to be heated over a flame (or other heat source); it would cause the cheese to melt and essentially make the item useless.

it’s a pastiche to the idiom - “As useful as a chocolate teapot” - which would have similar disastrous effects.