In a large bowl, combine the crumbs, sugar, and butter and stir until well blended. The mixture should stick together when squeezed firmly in your hand.
Transfer the Graham-cracker mixture to a 9-inch springform pan and press the mixture firmly onto the bottom of the pan. Bake until golden brown, about 8-10 minutes. Remove from the oven and let it cool.
For the filling, in the bowl of a stand mixer, beat together the cream cheese, mascarpone cheese, powdered sugar, and vanilla extract until thick and creamy. Add the eggs, one at a time and continue mixing until the mixture is well blended.
Add the passion fruit pulp and continue beating, scraping down the sides of the bowl as needed. Add the sour cream and beat for another 5 minutes.
Pour the filling into the spring-form pan and bake in the oven for 45 minutes. It might still jiggle a bit. Let it cool for 10 minutes.
For the topping, combine sour cream, sugar, and vanilla extract and beat until the mixture becomes creamy. Pour the sour cream mixture on top of the filling and bake until the top is firm but still soft to the touch, about 15 minutes.
Remove the cheesecake from the oven and let it cool for 30 minutes. Transfer the cake to the refrigerator and chill overnight.
For the syrup, place the sugar, water, and passion fruit pulp in a saucepan over low-medium heat and boil until the mixture volume is halved or until syrupy, about 20 minutes.
To serve, run the edge of a warm knife along the inside edges of the springform pan. Remove the cheesecake and top with passion fruit syrup.
If you want a smooth texture, strain the passion fruit pulp before using.