01 -  In a large mixing bowl, beat cold heavy whipping cream with an electric mixer until soft peaks form. 
 02 -  Gradually add sweetened condensed milk to the whipped cream and continue mixing until stiff peaks form and the mixture is light and smooth. 
 03 -  Arrange a single layer of graham crackers at the bottom of a 23 x 33 cm baking dish, trimming crackers as needed to cover the base completely. 
 04 -  Evenly spread one third of the whipped cream mixture over the graham crackers. 
 05 -  Arrange a layer of thinly sliced mangoes over the cream to ensure full coverage. 
 06 -  Repeat the layers of graham crackers, cream mixture, and mangoes two more times, finishing with a final layer of mango slices. 
 07 -  Cover the baking dish with plastic wrap and refrigerate for at least 6 hours or overnight to allow the graham crackers to soften and the dessert to set. 
 08 -  Slice into portions and serve chilled for optimal texture and flavor.