For the bases: Preheat oven to 175S. Cover with baking paper the bottoms of two trays with a diameter of 23 cm and greased them. In a small bowl, sift the cocoa, flour, starch and baking powder. Stir until knead well. With a mixer, beat the eggs with the sugar and salt until a fluffy cream. Add the mixture of cocoa, flour and starch three times after each addition was stirred gently with a spoon until the dry mixture is absorbed by the egg. Spread mixture evenly in oiled baking dish. Bake in preheated oven 20-25 minutes until the base becomes elastic and lightly pressed with your finger immediately regain their shape. Remove the drip trays from the oven and turn the grid on the bases. Leave it to their full cooling. For the syrup: Heat 2/3 cup water and sugar, stirring to dissolve sugar. Cool and add the liqueur. For the cream: Break the chocolate into small pieces. Heat the cream on the stove with the butter and add the chocolate. Stir over low heat until chocolate is completely melted and a smooth mixture. Cool and set aside for two hours the mixture until firm and become cream from time to time stirring. Assemble the cake: Remove the paper from the bases and with a long knife or thread cut them in two . Place one base into the cake pan, spray with 1/4 of the syrup, pour 1/4 of the cream and spread well across the base. Repeat with the other three the base. Place the cake for at least 10 hours in the fridge, and the best night.