I used chopped raw cacao butter in this to give the flavor of white chocolate but you can just use extra chocolate chips if you prefer. (joyfilledeats.com)
By the way, if you don't have vegan chocolate, you can mix melted cacao butter with cocoa powder and sweetener of your choice. (myhealthydessert.com)
Melt the raw cacao butter in a warm water bath or in a small saucepan on low heat. (tuulia.co)