01 - 
                Line a 20 x 20 cm or 23 x 23 cm pan with parchment paper or aluminium foil and lightly grease. Set aside.
              
              
              
                02 - 
                In a medium saucepan over medium heat, add granulated sugar, unsalted butter, and heavy cream. Stir continuously until the mixture reaches a rolling boil.
              
              
              
                03 - 
                Continue stirring while boiling for 4 minutes. The mixture should become smooth and slightly thickened.
              
              
              
                04 - 
                Remove the saucepan from heat. Immediately add marshmallow creme and white chocolate chips. Stir until melted and the mixture is smooth.
              
              
              
                05 - 
                Mix in rum extract or dark rum, salt, and ground nutmeg if desired.
              
              
              
                06 - 
                Quickly pour the mixture into the prepared pan and smooth the surface with a spatula.
              
              
              
                07 - 
                Allow to cool at room temperature for 30 minutes. Transfer to the refrigerator and chill for at least 2 hours until fully set.
              
              
              
                08 - 
                Once firm, cut into squares. Store in an airtight container at room temperature for up to a week or refrigerate for extended freshness.