Combine flour, sugar, cocoa and salt in medium bowl. Add butter and rub in, using fingertips, until mixture forms looks pebbly. add water and egg yolk and mix in with fork until well incorporated.

Gather dough and shape into a flattened circle, then wrap in plastic wrap. Chill for 20 minutes.

(Alternatively, ingredients can be pulsed in the bowl of a food processor, which helps prevent the butter from melting from the heat of your hands)

Heat oven to 375°F. (350°F for convection ovens)

Butter and flour a 9-inch tart pan with 1-inch-high sides and a removable bottom. Roll out dough between 2 sheets of waxed paper to a 10-inch circle.

Peel off 1 waxed paper sheet. Invert dough into prepared pan, press evenly to fit, including up the sides of the pan. Freeze until firm, about 10 minutes.

Peel off second waxed paper sheet and trim edges.

Line crust with foil; fill with dried beans or pie weights. Bake until crust is set, about 12 minutes. Remove foil and beans. Bake until crust just begins to darken around edges, piercing with toothpick if crust bubbles, about 12 minutes longer. Remove from oven and maintain oven temperature.

Spread jam over bottom of crust. Bake until jam is set, about 3 minutes. Transfer pan to rack; cool completely.

Bring cream to a boil in a small, heavy saucepan. Remove from heat.

Add chocolate and whisk until melted and smooth. Transfer chocolate ganache to bowl and refrigerate until chilled but not firm, about 30-45 minutes.

Using electric mixer, beat ganache until very thick and semifirm. Spread ganache over jam in crust.

Arrange raspberries atop ganache.