Preheat oven to 180°C.
1. Grease with oil a roll mould with dimensions 30x25x2 cm.
2. Place on the base and the sides baking paper and grease the baking paper with oil. With an electric beater, beat the eggs in a bowl for 4-5 minutes or until they become fluffy.
3. Add sugar slowly, continuously beating until the mixture becomes shiny.
4. Transfer the mixture to a large bowl. With a metal spoon, add the sifted flour, cocoa, bitter chocolate and water.
5. Spread the mixture in the baking tin, even out the surface. Bake the roll for 12-15 minutes until it browns.
6. Put a sheet of baking paper on a dry towel. Sprinkle it with the extra sugar. Remove the roll from the baking paper and let it sit for 2 minutes.
7. Carefully, roll it with the baking paper and let it sit for 5 minutes. Remove baking paper and discard it.
8. Spread the whipped cream and the raspberries on the roll. Roll it again.
