01 - Combine flour, sugar, and salt in a bowl. Cut in cold butter until mixture resembles coarse crumbs. Add egg yolk and 1-2 tablespoons cold water, mixing just until dough holds together. Flatten into a disk, wrap in plastic, and refrigerate for 30 minutes.
02 - Roll dough on a lightly floured surface to fit a 9-inch tart pan. Press dough into pan, trimming any excess. Prick the base all over with a fork.
03 - Freeze crust for 10 minutes. Preheat oven to 375°F. Line crust with parchment paper and fill with pie weights. Bake for 15 minutes, remove weights and paper, then bake 5 more minutes until golden. Cool completely.
04 - Heat cream in a small saucepan until just simmering. Pour over chopped chocolate in a heat-proof bowl. Let sit for 1 minute, add butter, and stir until smooth and glossy.
05 - Pour ganache into cooled crust. Smooth top and refrigerate for 45-60 minutes until set but still slightly soft.
06 - Arrange fresh raspberries over the ganache. For a glossy finish, warm raspberry jam with water and gently brush over the berries. Serve chilled or at room temperature.