Beat the eggs, icing sugar and vanillin sugar with the whisk of the hand mixer until creamy. Mix the oil and eggnog. Mix flour and baking powder and stir in alternately with the advocaat mix.
Grease a box form (approx. 12 x 30 cm) and sprinkle with flour. Pour in the dough and bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 60-70 minutes (test with sticks).
Cover the cake with aluminium foil if it gets too dark.
Remove the cake from the oven, turn out of the tin after about 20 minutes and let it cool down on a cake rack. Coarsely chop the chocolate coating and coconut oil. Melt both in a bowl over a warm water bath.
Cover the cooled cake with the chocolate coating and chill for approx. 30 minutes.