Prepare the Tart Shells:

1. Make the Dough: In a food processor, pulse the flour, powdered sugar, and salt until combined. Add the cold butter and pulse until the mixture resembles coarse crumbs.
2. Add Wet Ingredients: Add the egg yolk, vanilla extract, and ice water. Pulse until the dough just starts to come together.
3. Chill the Dough: Shape the dough into a disc, wrap it in plastic wrap, and refrigerate for at least 30 minutes.
4. Roll and Cut: On a lightly floured surface, roll out the dough to about ⅛-inch thickness. Cut into circles slightly larger than your tartlet molds.
5. Fit into Tart Molds: Press the dough into greased tartlet pans, trimming any excess. Prick the bottoms with a fork.
6. Pre-Bake: Preheat your oven to 350°F (175°C). Line each tart shell with parchment paper and fill with pie weights or dried beans. Bake for 10 minutes, then remove the weights and bake for another 5 minutes until golden brown. Let them cool completely.

Make the White Chocolate Ganache:

7. Heat the Cream: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer.
8. Melt the White Chocolate: Pour the hot cream over the chopped white chocolate. Let it sit for 1-2 minutes, then stir until smooth.
9. Add Vanilla: Stir in the vanilla extract for added flavor. Let the ganache cool slightly before filling the tart shells.

Assemble the Tartlets:

10. Fill the Tartlets: Spoon or pipe the white chocolate ganache into the cooled tart shells, filling them about ¾ full.
11. Chill: Refrigerate the tartlets for at least 30 minutes to allow the ganache to set.
12. Add Raspberries: Arrange fresh raspberries on top of each tartlet.
13. Glaze (Optional): Warm the raspberry preserves slightly and brush over the raspberries for a glossy finish.
14. Garnish: Sprinkle with white chocolate shavings if desired.