Fill a dome-shaped silicone mold full with red velvet ice cream. Place in the freezer for 10-20 minutes, until the ice cream has stiffened. Scoop some ice cream out of the center and fill it with the vanilla ice cream. Return the mold to the freezer for 6-8 hours or until fully set.

Unmold the tartufo onto a wire rack and sift some cocoa powder on top, until the entire surface is covered. These can be returned to the freezer to store, or serve them on a plate and slice to reveal the layers inside!