½tspcoarse Kosher salt(if using table salt, use half the amount)
1can (14 oz)sweetened condensed milk
¾cupgood-quality blueberry jam
In a large bowl, beat the cold heavy whipping cream with the vanilla and salt until soft, fluffy peaks form.
Add the sweetened condensed milk and beat until well combined.
Pour the ice cream mixture into a lidded ice cream container. Freeze for several hours (at least 3-4), until it begins to thicken and firm up. The ice cream will be more solid around the edges, so you can stir it a few times to help it freeze more evenly.
Once the ice cream is getting cold and thick, dollop the blueberry jam on top and swirl it in. (If you add the jam before the ice cream starts to freeze, the jam will just sink to the bottom of the container.)
Return the ice cream to the freezer and freeze until firm enough to scoop, at least 6-8 more hours, or overnight.