01 - Blend flour, powdered sugar, and salt in a food processor. Add cold butter and pulse until mixture resembles coarse crumbs. Add egg yolk and 1 tbsp cold water; pulse just until dough comes together, adding more water as needed.
02 - Shape dough into a disk, wrap in plastic, and refrigerate for 30 minutes.
03 - Preheat oven to 350°F. Roll out dough on a lightly floured surface to fit a 9-inch tart pan. Press into the pan and trim excess. Prick base with a fork and chill for 10 minutes.
04 - Line crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes; remove weights and bake 8-10 minutes more, or until golden. Cool completely.
05 - Place chopped chocolate in a heatproof bowl. In a small saucepan, bring cream just to a simmer. Pour over chocolate and let stand 1-2 minutes. Add butter, then stir gently until smooth and glossy.
06 - Pour ganache into cooled crust, smoothing the top. Refrigerate for 1 hour, or until set.
07 - Arrange raspberries on top. For a glossy finish, warm raspberry jam and brush gently over berries.
08 - Serve chilled or at room temperature.