In a large bowl, beat the butter and icing sugar with a hand mixer until the mixture is fluffy and pale yellow.
Add the flour, vanilla, and egg, then mix well until a dough forms.
Roll out the dough into a 5mm thick sheet. Using a large cookie cutter, cut out discs about 9cm in diameter. Transfer to parchment paper and refrigerate for 30 minutes.
Lightly grease a muffin pan with melted butter. Press the chilled dough discs into each muffin mould, covering the bottom and sides. Using a fork, poke a few holes into the bottom of each pastry.
Bake in an oven preheated to 180�C, for 15 to 20 minutes. Then let it cool to room temperature.
Using a food processor or blender, pulse the durian flesh until it's smooth and creamy.
In a large bowl, cream together the cream cheese and icing sugar with a hand mixer, until the mixture is fluffy and creamy.
Add in the durian flesh and egg yolks, then whisk to combine.
In a separate bowl, beat the egg whites with sugar until soft peaks form. Gently fold the egg whites into the durian mixture until smooth.
Add the filling to the tarts and bake for another 10 minutes in an oven preheated to 185�C.
