Whenever I use silicone moulds to make chocolate, I start to get this powdery residue after washing. I've tried soaking them in boiling soapy water, I've given them a good scrub with the sponge, but it remains. I've seen one post online saying it might be cocoa butter? But I can't find anything definitive. Does anyone know what it is and if it's harmful? It only appears after I've made chocolate in it a few times. If it makes a difference, I used plain chocolate with additional mint or orange oil. Sometimes I put it in the freezer to help it set faster. #cookinghelp #bakinghelp #askfedi #siliconemoulds