Pulse or crush the chocolate crackers into crumbs then, mix the crumbs with the melted vegan butter,
Firmly press into the bottom of a cake ring lined with acetate sheet to create a compact base.
Refrigerate the base to set while preparing the mousse layers.
On a double boiler, melt the vegan dark chocolate with the heavy cream. Fold the whipped cream into the warm melted chocolate until smooth.
Pour over the set cake crumb base and refrigerate until the mousse is firm.
Repeat the process used for the dark chocolate mousse, using vegan milk chocolate this time.
Once the dark chocolate layer sets, carefully pipe the milk chocolate mousse on top. Return to the refrigerator to set.
Melt the vegan white chocolate with the heavy cream. Fold the whipped cream into the melted white chocolate until well combined.
Pipe the white chocolate mousse on top of the firm milk chocolate mousse.
Freeze or refrigerate the cake until completely set, ideally overnight.
Cover the cake with dustings of cacao powder on top. Remove the acetate cake sheet and cake ring before serving.