Or for a more traditional volcano, use mod roc and cover with clingfilm so you can reuse it over and over again! (mummymummymum.com)
After about 1 hour, your bars should be fully set and can be stored in the fridge or wrapped in clingfilm for taking out and snacking on the go! (traineatgain.com)
Allow to cool, then transfer to the fridge with a piece of clingfilm placed directly on the surface of the curd to cool completely. (lapechefraiche.com)