Chill mixing bowl and beaters in freezer for 30 minutes.
Whip heavy cream to stiff peaks.
Mix condensed milk and vanilla extract in separate bowl.
Gently fold whipped cream into condensed milk mixture in three batches.
Add milk by tablespoon until desired consistency is reached.
Transfer to container, cover with parchment and lid.
Freeze at least 6 hours, preferably overnight.
Let sit 5-10 minutes before serving.
