Preheat the oven to 325°F. Sift the flour into a bowl with sugar, baking powder and cocoa then make a hole in the center.

Separate egg yolks from whites. Mix oil with warm water using a whisk, pour in the middle of the sifted dry ingredients along with egg yolks. Stir with the whisk to obtain a homogeneous batter.

Add a few drops of lemon juice to the egg whites and beat until stiff.

Add the egg whites to the cake batter little by little, stirring gently bottom up.

Pour the cake batter in a 7 inch chiffon cake pan. Bake for 1 hour and 15 minutes.

Cool the chiffon cake completely upside down, then run a knife around the pan edges to turn cooled cake out onto a serving plate.

Melt dark chocolate in a double boiler, add the milk slightly heated. Stir until you have a smooth and shiny glaze to drizzle over the top of the cake.