To make the dough, place the sugar, butter, and vanilla extract in the food processor. Pulse until combined. Add flour, salt, and egg. Process until combined.
Form a disk out of the dough, wrap in plastic wrap and refrigerate for a minimum of a 1/2 hour. When dough is slightly chilled, lay it between 2 sheets of plastic wrap and roll out using a rolling pin to 1/8th-inch thickness.
Remove the top layer of plastic wrap and flip the dough into an ungreased tart pan. Remove the second piece of plastic wrap and press the dough into the bottom and sides of the pan. Use the rolling pin to fill across the top of the tart pan, cutting off excess dough.
Using a fork, prick holes into the tart. Bake for 15-20 minutes until golden. Remove from oven and allow to cool.
Reduce oven temperature to 275F.
While crust is cooling, pour cream, milk, sugar and cinnamon stick into a saucepan and bring to a boil, stirring to dissolve the sugar. Discard cinnamon stick.
Pour hot cream mixture over the chocolate and mix together until chocolate is completely melted. Gently stir to combine.
Whisk egg in a bowl and pour about 1/4 of the chocolate mixture over the egg to temper. Stir to combine. Return egg mixture to the remaining chocolate mixture and gently stir until smooth.
Fill the cooled crust with the chocolate custard.
Carefully transfer tart to the oven and bake at 275F for about 30 minutes, until set. Transfer the tart on the sheet pan to a wire rack and cool completely, at least 3 hours.
Garnish tart with raspberries, mint leaves, and a light pinch of coarse Himalayan pink salt (optional). Serve chilled or at room temperature.