White chocolate sauce from cocoa butter?

I just bought some Torani white chocolate sauce, but it's absolutely awful. Per tablespoon there is less than 1g fat which suggests there is barely any cocoa butter present.

I'd like to make my own but any recipes I can find suggest using white chocolate bars.

I figure that using cocoa butter would make for a richer flavour, and will be more cost effective.

Does anyone have a recipe or can suggest how much of the butter to use ?

bon appetit