01 - Whisk together milk, cream, sugar, cocoa powder, and salt in a medium saucepan. Heat over medium heat, stirring frequently, until the mixture is hot and sugar is completely dissolved. Do not let the mixture boil.
02 - Remove the saucepan from heat and stir in vanilla extract. Pour the mixture into the Ninja Creami pint container and allow it to cool to room temperature.
03 - Cover the container and freeze for at least 8 hours or overnight until completely solid.
04 - Process the frozen base in the Ninja Creami using the Ice Cream setting according to manufacturer instructions.
05 - Create a well in the center of the processed ice cream. Add marshmallow fluff, caramel sauce, and chocolate fish or pieces into the well.
06 - Reinsert the pint and run the Mix-In setting to swirl the toppings throughout the ice cream. Serve immediately for soft-serve texture, or freeze for 1-2 hours for firmer scoops.