• Preheat the oven to 350 degrees.
• For the crust, place the chocolate wafers and sugar in the bowl of a food processor fitted with the steel blade and process until finely ground. Pour into a medium bowl and stir in the butter. Press the mixture evenly into the bottom and sides of a 9-inch tart pan with a removable bottom. Place on a sheet pan and bake for 10 minutes. Set aside.
• Meanwhile, for the filling, place the 6½ ounces of chocolate in a medium bowl. Heat the 1¼ cups cream in a small saucepan until it just comes to a boil. Pour the cream over the chocolate, allow it to stand for one minute, then stir gently with a whisk until smooth (see note). Stir in the eggs and vanilla, whisking until smooth. Pour into the crust and bake for 18 to 20minutes, until the filling is set on the edge but still jiggly in the middle. Set aside to cool.
• For the glaze, put the 3 ounces of chocolate and the coffee granules in a small bowl. In the same saucepan, heat the ¼ cup cream just to aboil and pour it over the chocolate. Allow to sit for one minute, then whisk until smooth. Gently pour the glaze over the chocolate filling (not the crust)and spread to the inside edge of the crust with a knife or offset spatula. Sprinkle with the sea salt and set aside at room temperature until set. Remove the rim of the tart pan and transfer to a flat serving plate. Cut in wedges (the crust may crumble a little) and serve at room temperature.

Make-Ahead

• If either chocolate-and-cream mixture doesn’t melt completely, heat in a microwave for 15 seconds, then stir well.
• If you’d like to serve with a sauce, make a quick crème anglaise by melting vanilla ice cream and drizzling a puddle on the plate before plating each wedge of the tart.