Cut the cheeks of the mangoes away from the pit. Using a spoon/cup remove the flesh from the skin. Thinly slice the flesh lengthwise. Set aside.
Pour the thickened cream and condensed milk into a large bowl. Using a hand mixer, whip on medium-high speed until doubled in size and thickened to soft peaks.
Pour the juice in a shallow bowl. One at a time, quickly dip the biscuits in the juice and arrange a single layer on the bottom of a serving dish.
Top the biscuits with ⅓ of the cream mixture. Using a spatula or spoon, spread the cream out evenly.
Add a layer of sliced mango. Repeat this process twice so there are 3 layers of biscuits and cream. Arrange the remaining mango slices as the top layer of the cake, overlapping for design.
Cover and refrigerate for at least 6 hours or overnight.
Once chilled, remove from the fridge. Crush up the digestive biscuits and sprinkle over the top. Cut into squares and serve.