01 - In a food processor, blend flour, powdered sugar, and salt. Add cold butter and pulse until mixture resembles coarse crumbs. Add egg yolk and 1 tablespoon 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 to allow gluten to relax.
03 - Preheat oven to 350°F. Roll out dough on lightly floured surface to fit a 9-inch tart pan. Press into pan and trim excess. Prick base with fork and chill for 10 minutes. Line with parchment and fill with pie weights. Bake for 15 minutes; remove weights and bake 8-10 minutes more until golden. Cool completely.
04 - Place chopped chocolate in heatproof bowl. In 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.
05 - Pour ganache into cooled crust, smoothing top. Refrigerate for 1 hour or until completely set.
06 - Arrange fresh raspberries on top of set ganache. For glossy finish, warm raspberry jam and brush gently over berries.
07 - Serve chilled or at room temperature. Best enjoyed same day for optimal crust texture.