Preheat the oven to 350°F (175°C). In a mixing bowl, combine all-purpose flour, powdered sugar, and salt. Blend in softened unsalted butter until the mixture resembles coarse crumbs.

Add the egg yolk and a splash of cold water, mixing gently until the dough holds together. Shape it into a disk, wrap it in plastic wrap, and chill in the refrigerator for 30 minutes.

Roll out the chilled dough to about 1/8 inch thick. Press the rolled dough into a tart pan and prick the bottom with a fork. Bake for 15–20 minutes until golden brown, then let cool completely.

In a small bowl, dissolve unflavored gelatin in warm milk. In a separate bowl, whip heavy cream with granulated sugar and vanilla extract until soft peaks form.

Gently warm the gelatin mixture until fully dissolved. Fold it into the whipped cream gently until combined.

Fill the cooled tart crust with the vanilla cream filling. Refrigerate for at least 2 hours to allow the filling to set.

Top with fresh raspberries before serving, arranging them attractively.

Slice the tarts carefully and serve chilled.