How to make white chocolate using only sugar and cacao butter?

You can not make chocolate from just sugar and cacao butter you're missing chocolate solids. Chocolate is only created with three primary ingredients: the chocolate solids (ground dried and fermented cacao nibs that have been separated from most their fats), cacao or cocoa butter that's naturally contained inside chocolate solids in various percentages along with added sweetener to taste (sometimes none required depending on cacao bean), as well as optional flavours to make white chocolate you would then use milk solids that you would source separately.