Beat yolks with half the sugar. Add oil, milk. Slowly add the flour with baking powder and vanilla.
Proteins are broken down separately. Add to the above mixture and stir gently to offer consistent mixture.
From this mixture child that can do several versions of the cake:

Option 1 - Plain cake - do not add anything else. This is prepochitaniya me option.

Option 2 - With cocoa - 1 / 3 of the mixture is separated and added cocoa to make it darker. Shaped cake Pour 1 / 3 vanilla mixture, 1 / 3 of cocoa mixture, and finally 1 / 3 vanilla mixture. More beautiful is being cut, but I think zhariant 1 is more palatable.

Option 3 - With chocolate bars - to add chocolate mixture sticks or crushed chocolate.

Form cake is smeared with oil and blind with flour. Pour the mixture into cake form. Bake at 180-200 on Check whether it is ready with a toothpick - pierce the cake in several places and there should be no batter adhering to the toothpick.
After removing from oven to ostavchme poizstine 15-20 minutes and then removed from the form. Sprinkle with plenty of powdered sugar while warm.