In a medium saucepan, cook the apples, butter, cinnamon and brown sugar over medium low heat. Cook for 8-10 minutes, or until the apples are softened. Allow to cool.
Once the apples are cooled, mix in the vanilla.
In the bowl of a stand mixer fitted with a whisk attachment, whip the heavy cream until stiff peaks form.
Slowly fold in the apple mixture and the sweetened condensed milk.
Pour into an airtight container and allow to harden in the freezer for around 8 hours.