Beat the eggs with the sugar and vanilla in a bowl. Pour the oil in a thin trickle while beating nonstop. Pour in the water and stir. Mix the flour with the baking powder and gradually add it to the mixture.
Stir to obtain a homogeneous mixture. Pour it into an oiled and floured form. Bake in a preheated 356°F (180 °C) oven about 40 min. Take it out and leave to cool.
Heat the cream and crumble the chocolate in it. Stir until fully dissolved and pour it over the cooled cake.