01 - Combine flour, sugar, and salt in a bowl. Cut in cold butter until mixture resembles coarse crumbs. Add egg yolk and 1-2 tbsp cold water, mixing just until dough forms a ball. Flatten into a disk, wrap in plastic, and refrigerate for 30 minutes.
02 - Roll chilled dough on lightly floured surface to fit a 9-inch tart pan. Press dough into pan, trim excess edges, and prick base all over with fork.
03 - Freeze crust for 10 minutes. Preheat oven to 375°F. Line crust with parchment paper, fill with pie weights, and bake for 15 minutes. Remove weights and paper, then bake 5 additional minutes until golden brown. Cool completely.
04 - Heat heavy cream in small saucepan until just simmering. Pour hot cream over chopped chocolate in a heat-proof bowl. Let stand for 1 minute, then add butter and whisk until completely smooth and glossy.
05 - Pour ganache into cooled tart shell. Spread evenly and refrigerate for 45-60 minutes until set but still slightly soft to the touch.
06 - Arrange fresh raspberries over ganache in decorative pattern. For glossy finish, warm raspberry jam with water and brush gently over berries. Serve chilled or at room temperature.