Position an oven rack in the center of the oven and pre-heat the oven to 350 degrees F.
In a large bowl, sift together the flour, baking soda, and salt; set aside.
In the bowl of an electric mixer, cream the butter and the sugar until light and fluffy. Add the cooled chocolate and vanilla and beat for 3 minutes to incorporate. Beat in the eggs one at a time.
Scrape down the sides of the bowl and beat for another 3 minutes. Gradually mix in the dry ingredients in 3 batches, alternating with the cold water. Beat for 1 minute after each addition to incorporate the ingredients. Mix until the batter is smooth.
Coat 2 (9-inch) round cake pans with non-stick cooking spray. Cut 2 circles of parchment paper to fit the pan bottoms and place them inside the pans; then spray the paper for added non-stick insurance.
Pour batter into the prepared pans and smooth the surface with a spatula; the pans should be 2/3 full. Bake for 30 to 35 minutes. The cake is cooked when a toothpick inserted in the centre comes out clean and the cake springs back when touched
Leave to cool for 40 minutes. Turn the cakes out of the pans and remove the paper. Drizzle them with a few tablespoons of Chambourd.
With a metal spatula, spread 1/2 cup butter cream on top 1 of the layers. Start in the center and work your way out.
Carefully place the second layer on top. Smooth the sides with butter cream, then spread the rest over the top so that the cake is completely covered. Refrigerate for 5 minutes before decorating or cutting.
With a large knife scrape some shavings from a block of dark chocolate. Scatter shavings over cake.