(repasted an answer to someone else bc I'm lazy)
Chocolate is made from cocoa butter & cocoa powder which are both derived from grinding cocoa seeds. White chocolate is made without cocoa powder (like the stuff you put in chocolate cakes, it's quite bitter without sugar and milk) while cocoa butter is just the fat from the cocoa seed, it's white and has a nutty flavor that's without bitterness. So they actually do need cocoa seeds to make white chocolate!
A lot of things nowadays are chocolate "flavored" which means they don't contain any chocolate, just artificial flavoring. Cocoa butter is also expensive, so they often use cheap replacements for some or all of it in chocolate, which might be why some white chocolate technically has no cocoa products in it, but high quality stuff like in the manhwa does. :)
It's white because it doesn't have cocoa powder, which means they could have made it on their own after a few trial runs. Going all the way to an Island to get help from a chocolate empire had to be an excuse for exclusive access to drinks made with white chocolate. If not, then our MC is just being nice.