Whip the pint of heavy whipping cream until stiff peaks form.
Fold the sweetened condensed milk, 1/2 of the marshmallow cream, and the vanilla into whipped cream.
Pour into a loaf pan.
Top with remaining marshmallow cream and swirl with a knife.
Tightly cover the pan with plastic wrap and place it in the freezer for 8 hours or overnight, until firm.
Video
Notes
One: Chocolate
Stir six ounces of melted, cooled chocolate into the ice cream mixture.
Two: Toasted
Spread half of the marshmallow fluff on a rimmed baking sheet and toast it under the broiler. Allow it to cool before adding it to the ice cream mixture.
Three: Sandwiches
Put scoops of ice cream on graham crackers (or cookies). Top with another graham cracker, squish the ice cream between them and place them in the freezer to harden.
Four: Storage
Store in an airtight container in the freezer for 2-4 weeks.