For the cake: Heat a skillet full of water to a bare simmer. In the large bowl of an electric mixer, whip eggs on high speed for 5 minutes. To the eggs add sugar, salt and vanilla and combine. Set the bowl into the hot water bath to heat the mixture to between 110 and 120 degrees F. Stabilize the mixture by whipping on medium speed for 15 more minutes.
Meanwhile sift together the bread flour, the cocoa powder, and the pastry flour. Prepare the baking pans by greasing 2 (6-inch) diameter round pans and dusting with flour.
Gradually fold the sifted dry ingredients into the egg mixture by hand. Slowly pour in the oil while folding. Fill the pans approximately 2/3 full with the batter and place immediately in the oven. Bake in preheated oven for 25 to 30 minutes. (The surface of the cake should spring back when touched.) Cool 10 minutes in the pans, then remove to wire racks to let cool completely.
For the syrup: Combine the sugar, water, cherry brandy, and cream of tartar in a small saucepan. Cook over low heat stirring only until the sugar is dissolved and the syrup is hot. Cover and simmer gently for 2 minutes. Remove from heat, uncover and let cool.
For the cherry filling: Place cherries in a small saucepot and add brandy, stirring to coat cherries. Heat over medium low heat until most of liquid evaporates, then remove from heat and let cool.
For the pastry cream: Reserve 2 tablespoons of the milk then combine the rest of the milk with half the sugar and bring to a gentle boil. In a small bowl whisk the 2 tablespoons of reserved milk into the cornstarch to create a slurry. Add the other half of the sugar and then the eggs to the slurry and whisk to completely combine. Temper the egg mixture with the boiling milk. (This is done by spooning some of the milk into the egg mixture to equalize temperatures without cooking the eggs.) Return all liquids to the pot and bring to a boil, whisking constantly. Cook for 1 minute. Remove the milk mixture from the heat and whisk in butter and vanilla extract. Pour into a large pan, put plastic wrap directly on the surface, and allow to cool.
Slice each of the cake rounds (horizontally) into 3 (1/2-inch) thick layers using a long thin knife or taut wire. Place the layers onto baking sheets (which have a rim) and pour cherry syrup over the layers, allowing them to soak.
For the cream topping: Whip the heavy cream and sugar with an electric mixer to a medium peak.
Assemble the cakes by spreading a layer of the pastry cream on the bottom layer, then placing brandied cherries on top. Place a second layer on top of cherries and repeat. Top with final layer of cake. (Each cake will have 3 layers.) Frost top layer of cake with whipped cream topping and garnish with cherries and chocolate shavings.