Turkish moist sponge cake. Classic recipe

For the biscuit:
֍ 2 eggs
֍ milk 140 ml
֍ vegetable oil 140 ml
֍ flour 140 g
֍ cocoa 3 tbsp
֍ baking powder 1 tsp
֍ salt
֍ vanilla sugar 1 tsp

For filling:
֍ milk 160 ml
֍ sugar 80 g
֍ cocoa 2 tbsp
֍ vegetable oil 50 g