Have ice cream maker already assembled according to package instructions.
In a large bowl, combine heavy cream, milk, marshmallow fluff, vanilla extract & salt. Using a handheld electric mixer on low speed beat ingredients for about 3 to 5 minutes until thoroughly combined. Mixture may be foamy and you'll still have some small clumps of marshmallow fluff, this is fine.
Pour ice cream mixture into ice cream maker and follow package instruction for allotted time of churning. My machine calls for 25-30 minutes of churning, so I let the ice cream churn for 30 minutes.
Once ice cream is done transfer the soft serve ice cream to a loaf pan or tupperware container and cover with plastic wrap or the appropriate lid. Allow ice cream to freeze in the freezer for 4 to 6 more hours to proper firm up. When ready to serve simply remove from freezer, scoop & serve!