Preheat the oven to 350°F (175°C).

In a food processor, combine the flour, cold butter, and powdered sugar. Pulse until the mixture resembles coarse crumbs.

Add the egg yolk and cold water to the crumb mixture, pulsing until the dough comes together.

Turn the dough out onto a lightly floured surface and knead it gently until smooth. Wrap in plastic wrap and refrigerate for 30 minutes.

Roll out the dough on a floured surface to fit into a 12-cup tartlet pan. Press the dough into the bottom and sides of the pan, trimming any excess.

Line the tartlet shells with parchment paper and fill with pie weights or dried beans. Bake for 10-12 minutes, then remove the weights and parchment, and bake for an additional 5-7 minutes until golden brown. Let cool completely.

In a small saucepan, heat heavy cream over medium heat until it begins to simmer. Remove from heat and stir in the white chocolate chips until fully melted and smooth.

Add vanilla extract and mix well.

Pour the white chocolate ganache into the cooled tartlet shells, filling them about three-quarters full.

Place fresh raspberries on top of the ganache, and lightly brush the tops with raspberry jam.

Garnish with fresh mint leaves before serving.