Bring cream, milk and 3/4 cups sugar to a simmer over medium heat. Whip egg yolks, remaining sugar and violet extract in a bowl until smooth. When cream mixture reaches a simmer, temper into egg mixture, adding only a ladle at a time, to heat egg mixture without scrambling them. Return everything to heat. Stirring constantly, heat slowly to a temperature of 175F; strain and chill over an ice bath immediately. Once completely chilled, run the mixture in your ice cream machine.
For the Nitro Marshmallows:
Carefully drop marshmallows into liquid nitrogen for approximately 3-5 minutes. Strain nitrogen, only keeping the marshmallows. Serve frozen.
For the Pineapple Run Caramel Sauce:
Put sugar in a saucepot and bring up to a simmer over low-medium heat, taking care not to stir too much. Carefully add the rum and reduced pineapple juice with the pan away from the flame. Bring the mixture back to heat and simmer for 3 minutes. Serve warm.