Preheat your oven to 350°F (175°C).

In a medium bowl, beat the softened cream cheese with 3/4 cup of sugar until smooth. Add the eggs one at a time, mixing well after each addition. Stir in vanilla extract.

Pour the cream cheese mixture into the graham cracker crust, smoothing the top with a spatula.

Bake in the preheated oven for about 30 minutes, or until the edges are set and the center slightly jiggles. Allow the cheesecake to cool at room temperature for 30 minutes, then refrigerate for at least 3 hours.

To make the mango topping, combine 1 cup of mango nectar and 1/3 cup of sugar in a saucepan. Bring to a boil over medium-high heat, stirring to dissolve the sugar.

In a small bowl, dissolve the cornstarch in the remaining 1/4 cup of mango nectar, then stir into the boiling mixture until it thickens and becomes clear, about 30 seconds.

Place the diced mangoes in a bowl and pour the thickened mango sauce over them, tossing gently to combine.

Once the cheesecake is fully chilled, spread the mango topping evenly over the top before serving.