In a large bowl, mix the sweetened condensed milk, rosewater and ginger until homogeneous.
In a cold, medium bowl, whip the heavy cream until stiff peaks form, 5-10 minutes.
Add a spoonful of the whipped cream to the sweetened condensed milk, and mix until combined. This will make mixing the sweetened condensed milk into the whipped cream easier.
Add the remaining whipped cream to the sweetened condensed milk. Fold the whipped cream into the sweetened condensed milk just until there's not many lumps left, trying not to deflate the air in the whipped cream too much.
Transfer the ice cream to another container, cover, and freeze for at least 6 hours, up to 2 weeks.