Makes 1 8-inch tart
For crust, cream butter and sugar together. Stir in egg yolks, adding one at a time. Sift together flour, cocoa and salt and add to butter mixture. Mix until dough just comes together. Shape in to a disc and chill until ready to roll. If preparing ahead of time, pull dough from fridge an hour before rolling.
Preheat oven to 350F (180C). On a lightly floured surface, roll out dough to just over 1/4-inch thickness. Line an 8-inch removable-bottom tart shell with dough, trim edges and chill for 20 minutes. Dock pastry with a fork and bake for 18-20 minutes. Allow to cool.
For filling, reduce oven temperature to 325F (160C). Place chopped chocolate in a large bowl. Heat cream to just below a simmer and pour over chocolate. Let it sit for a minute then stir slowly. Stir in vanilla and chambord. Whisk an egg in a small cup then stir into chocolate. Pour into chocolate shell and bake for 12 minutes. Let cool for 15 minutes, then chill for 2 hours. Top with fresh raspberries up to 3 hours before serving.