In a pan on medium heat, mash the blueberries, then cook with the sugar and lemon juice until simmering and thickened enough to coat the back of a spoon
Use an electric mixer to whip the heavy cream until stiff peaks form
Add in the condensed milk, vanilla extract, and salt, then fold together
Fold in the blueberry compote, until the mixture is purple
Pour into a freezer-safe container
Arrange the reserved blueberries on top, then freeze for 5-6 hours, or overnight
