Pour the condensed milk, vanilla extract and cream into a large bowl or food mixer. Whisk using the balloon attachment or hand whisk until thick (the mix should hold it’s shape when you lift the whisk).
Gently stir in the chopped strawberries.
Take a loaf tin/pie tin or similar freezable container and spoon ½ of the cream mixture into it. Drizzle on ½ of the strawberry sauce, then repeat with the remaining and cream and sauce.
Swirl the mixture with the back of a knife – just enough to create a few swirls.
Sprinkle on the crumbled shortbread and place the ice cream in the freezer for at least 3-4 hours (cover with a lid or plastic wrap if freezing for longer).
Take the ice cream out of the freezer about 15 minutes before you want to eat it – to allow it to soften.