Boil the cream, invert sugar, and salt together. Pour a third at a time over the 123 g Guittard Onyx 72% Dark Couverture Chocolate Wafers and 21 g Guittard Éclipse du Soleil 41% Milk Couverture Chocolate Wafers them mix until emulsified.
Add 27 g Prova Gourmet Fusion Papua New Guinea Vanilla Flavored Cocoa Butter and mix with a hand blender, taking care not to create any air bubbles. Place in a piping bag and cool to 85°F.
Chocolate Shells
Melt the 200 g Guittard Onyx 72% Dark Couverture Chocolate Wafers and use the temperature curve method to temper the chocolate. Line polycarbonate molds with a layer of the tempered chocolate to make shells and leave to crystallize.
Fill shells with vanilla ganache (6g per mold). Leave to crystallize then seal with additional tempered chocolate.