To make the crust, place the flour, confectioner’s sugar and margarine into the bowl of a food processor fitted with a metal blade. Process for 10 seconds, until the mixture resembles sand. Add the egg yolk, water, and vanilla and process just until the dough comes together. Do not mix too much. Add the chopped chocolate and mix briefly to distribute. Place dough on a large piece of plastic wrap. Gather into a ball, cover and then flatten. Chill in the freezer one hour or overnight.

Preheat oven to 350 degrees Fahrenheit. Place an eight-inch tart ring or tart pan with a removable bottom on a parchment-covered cookie sheet. Grease the ring or pan with a little margarine.

Remove dough from freezer and let sit until it softens a little so it can be rolled. Place a piece of plastic wrap larger than the ring on the counter and sprinkle with flour. Place dough on top. Cover with a piece of parchment and roll on top of it to roll out the dough until it is at least one inch larger than the tart ring. Place your hand under the plastic, lift the dough and place in the tart ring using your finger to gently press the dough into the corners. Remove plastic and use a rolling pin to roll over the top to trim off excess dough.

Freeze 10 minutes. Line dough with foil or parchment and beans or pie weights. Bake for 20 minutes. Lift up the edges of the foil or parchment to remove it and the weights and bake another five minutes or until lightly browned. Remove from oven.

Bring the cream, soy milk and seeds of vanilla bean to boil in a medium saucepan. Remove from heat and add the chopped chocolate. Let sit for five minutes. Stir with a whisk. In a separate small bowl, whisk the eggs. Add 1/2 cup of the chocolate mixture and whisk in. Place this mixture into the saucepan with the chocolate and cream and whisk well. Scoop into the tart shell and bake for 25 minutes. Let cool and then chill in the fridge for three hours or overnight.