In a food processor, combine the flour, powdered sugar, and butter. Pulse until the mixture resembles coarse crumbs. Turn the dough onto a work surface, knead gently into a ball, flatten into a disk, and wrap in plastic wrap. Chill for at least 2 hours.

Lightly flour a work surface and roll out the dough to about 1/8 inch/0.3 cm thick. Fit into a 9-inch/24 cm tart pan with a removable bottom, pressing into the base and sides. Trim the edges and chill while preparing the filling.

Heat the oven to 320°F/160°C. In the bowl of a stand mixer fitted with the paddle attachment, beat the cream cheese, sour cream, and sugar on low speed until smooth, about 2 minutes. Add the eggs one at a time, mixing until incorporated. Add the pudding mix and beat until smooth and slightly thickened. Pour into the chilled crust.

Bake for 30 to 35 minutes, until just set around the edges. Reduce the heat to 300°F/150°C and bake for 25 minutes more, until the center barely jiggles. Cool to room temperature, then refrigerate until completely chilled, at least 4 hours or overnight.

To make the pistachio cream, heat the milk and pistachios in a small saucepan over medium heat until steaming. Transfer to a blender and blend until very smooth. Return to the pan, add the white chocolate, and stir gently until melted and smooth. Let cool slightly.

Pour the pistachio cream over the chilled cheesecake and use an offset spatula to spread evenly. Top with dried raspberries and refrigerate until set, at least 3 hours.