For the Chocolate Custard Brownie:
Preheat the oven to 350°F. Spray a sheet tray with nonstick spray, and line it with parchment paper. Melt chocolate over a double boiler. Allow to cool slightly. Cream the butter and sugar, then slowly add the eggs. Once all of the eggs have been incorporated, add the chocolate. Add the flour and salt and mix evenly. Spread the batter onto a sheet pan, and bake for 12 to 15 minutes. Allow the brownies to cool, and then freeze.
For the Espresso Granité:
Combine the water, sugar, lemon, and salt in a medium pot and bring to a boil. Add the espresso and stir, then cover to infuse. Strain the espresso mixture and pour it into a shallow pan. Freeze the mixture completely, then let the frozen mixture sit for 10 minutes at room temperature. Using a fork, scrape mixture into a granité and freeze.
For the Chocolate Pot de Crème:
Preheat the oven to 200°F. Combine the milk and sugar in a small pot, place over a medium heat and bring to a boil. Put the chocolate in a large bowl, and pour the hot milk mixture over the chocolate. Allow to sit for 5 minutes, then stir the mixture to form a ganache. Set the ganache over an ice bath to cool, and then whisk in the egg yolks. Strain the mixture and decant it into ovenproof dishes. Bake the dishes on a ½ sheet tray with a tray of water below to form a bain marie. When they are set, remove them from the oven, allow them to cool and then freeze them.
For the Roasted Cinnamon Cream:
Preheat the oven to 350°F. Roast the cinnamon sticks on a sheet tray for 10 minutes. Bloom the gelatin in cold water, then squeeze out the excess water. Combine the cream, sugar, and salt in a saucepan and bring to a boil. Add the roasted cinnamon and bloomed gelatin, stirring to break up the cinnamon. Cover the mixture and infuse it for at least 30 minutes. Strain and reserve the mixture overnight, covered. Whisk the cream until it becomes thick.
For the Liquid Pâte Sablé Sauce:
Gently warm the cream in a small pot over a low heat. Put the sugar in a separate pot and caramelize it. Deglaze the pan with the warmed cream. Add the milk, cocoa powder, salt and pâte sablé. Bring the mixture to a boil. Blend the mixture, cover with plastic wrap on top and keep warm until you’re ready to serve.
To Assemble and Serve:
Temper the chocolate and gently paint it onto acetate paper. When the chocolate is set, remove it from the acetate paper and cut it with a 7 centimeter x 7 centimeter square mold. Punch a 2 centimeter circle off center in the square of chocolate, and garnish it with gold leaf. Cut the frozen brownie and pot de crème components with the same square mold and put the pot de crème on top of the brownie to allow it to defrost. Plate the defrosted, chilled brownie with a layer of cinnamon cream, a scoop of espresso granité and finish it with the chocolate decoration. Plate the liquid pâte sablé sauce tableside, while warm.