Whip the cold heavy whipping cream until soft peaks form, about 3-5 minutes.

Incorporate sweetened condensed milk until stiff peaks form, 2-4 minutes.

In a 9x13-inch baking dish, layer graham crackers to cover the base.

Spoon one-third of the whipped cream mixture over the graham crackers evenly.

Add a generous layer of sliced mangoes over the whipped cream.

Repeat layering with more graham crackers, whipped cream, and sliced mangoes, finishing with whipped cream.

Cover with plastic wrap and refrigerate for at least 6 hours, or overnight.

Once chilled, slice into squares and serve on chilled plates.