01 - In a medium saucepan over low heat, combine the heavy cream and butter. Warm gently until the butter melts and the cream is just starting to simmer—do not let it come to a full boil.
02 - Add the chopped dark and milk chocolate to the warm cream. Stir constantly with a heat-proof spatula or wooden spoon until completely melted and smooth, ensuring no lumps remain.
03 - Remove the saucepan from heat. Stir in the vanilla extract and a pinch of sea salt until fully incorporated.
04 - Pour the chocolate mixture into a fondue pot or heatproof serving bowl. If using a fondue pot, light the burner or place a tea light underneath to keep the chocolate warm and fluid throughout serving.
05 - Arrange the marshmallows, fresh fruits, and cake cubes on a large serving platter or decorative board for easy access.
06 - Using fondue forks or long skewers, dip your chosen treats into the warm chocolate. Serve immediately while the chocolate maintains its silky, pourable consistency.