With a hand mixer, beat the whipping cream in a bowl until it doubles in size.
Add in condensed milk and vanilla extract. Mix until well-combined.
Layer the bottom of a glass baking dish with graham crackers. Break them into small pieces tp fill in the gaps.
Spread 1/3 of the cream mixture evenly on top of the graham crackers. Top the cream with sliced mangoes.
Place another layer of graham crackers, cream, and mangoes. Repeat this process once more, ending with a layer of sliced mangoes.
Cover and refrigerate overnight to set completely.
Slice and serve.