1. For the crust: Center a rack in the oven and heat to 350 degrees. Pulse hazelnuts in a food processor until coarsely chopped, about 3 to 4 pulses. Using a slotted spoon, remove 3/4 cup of the larger nut pieces and reserve for garnish.
2. Add flour, sugar, and salt to the remaining nuts in the work bowl and process for 20 seconds. Add butter and pulse until mixture resembles coarse sand. Add water, 1 tablespoon at a time, and pulse until a moist, crumbly dough forms (you may not need all 3 tablespoons).
3. Transfer to a greased 9" tart pan with a removable bottom. With lightly floured hands, press dough evenly into the bottom and up the sides of the pan.
4. Lightly pierce dough all over with a fork and freeze for 30 minutes. Transfer to oven and bake until crust is lightly browned, 20 to 25 minutes; transfer to a wire rack to cool.
5. For the filling: Place chocolate in a large bowl. Bring cream, vanilla, and salt to a simmer in a medium saucepan over medium heat. Pour over chocolate and let sit for 2 minutes without stirring, then add eggs and whisk until smooth.
6. Pour filling into the cooled crust and bake until center is just set, 20 to 25 minutes. While tart is still warm, top with reserved hazelnuts and sprinkle with sea salt (if using). Let cool for 30 minutes and refrigerate until very firm, 3 to 4 hours.
Source: Hannaford fresh Magazine, January-February, 2016