For the base: Bake in middle rectangular tray 40h50sm that stood with baking paper. Beat of very dense foam eggs with sugar (do not divide white and yolk), so as to increase its volume several times. Sift flour with cocoa, baking powder and salt. With slightly Russell add to the egg mixture to the absorption of the dry ingredients. Spread the mixture evenly in the pan and bake in pre-heated oven at 170C until ready. The finished base was allowed to cool and then cut into four equal-sized strips. For the cream: Mix the egg yolks, 5 tbsp sugar, flour and milk. Beating them well, no granules and boiling water bath until ready (thickening). I put the mixture in a container, which put on another with water as soon it brew steam from boiling water, that court does not touch the water. The butter is allowed to relax at room temperature and stirred fluffy foam with powdered sugar. Custard cool by placing the container in another container with cold water and stir frequently. So the cream will cool and will not catch the top crust. Once cooked cream is completely cool, proceed to mixing with the oil. Add a tablespoon or two of milk to cream butter and beat with a mixer at low speed until smooth for both mixtures. The other thing that you will need in the assembly of these pastes is 200 ml coffee lightly sweetened and may not sweeten and 50 g of dried cranberries admirably combine in your pastes with other flavors . For ease of use cake form zastelete stretch foil, the ends hanging out of the tray. Put tape on the base and sprinkle evenly with coffee. Top put a few spoonfuls of cream and spread evenly sprinkle with blueberries and again put some cream blur. Comes the next base, which again sprinkles coffee, then cream, blueberries and so on until organize your pastes. Finish with cream and cut into squares. Sprinkle a fine sieve with aromatic ground coffee.