Preheat oven to 175 C / Gas 3 to 4. Grease and flour a loose bottomed cake tin.
Cream butter in a bowl until light and fluffy. Gradually stir in sugar and vanilla sugar. Add one egg at a time, stirring well after each addition.
In a second bowl mix flour, baking powder, bicarbonate of soda and salt and sift. Combine yoghurt, vanilla extract and almond essence and stir into the egg mixture alternating with the flour mixture until well blended.
Tip mixture in the prepared cake pan and bake until a toothpick inserted in the centre of the cake comes out clean, 40 to 50 minutes.
Allow cake to cool in the tin for a little bit, then remove and let cool completely on a cooling rack.
When the cake is cool, cut out a 10cm circle in the centre of the cake with a glass, a biscuit cutter or a small cake tin.
Cut the surrounding cake ring into 6 equal pieces. Make sure not to cut into the circle in the centre.
For the chocolate filling place chocolate in a metal bowl. Heat cream in a saucepan until it just boils. Pour hot cream over the chocolate and whisk until melted and well combined.
Cut the centrepiece of the cake in half horizontally and spread a thin layer of the chocolate cream on the bottom half. Top with the other half and spread about half of the remaining chocolate cream over it.
Decorate to taste, before the chocolate is hardened. Place centrepiece on a cake serving plate and let cool.
Cut the side pieces of the cake in half horizontally as well and fill with chocolate cream.
For the butter cream beat butter until very fluffy and gradually add icing sugar. When the mixture gets stiff add some milk and vanilla extract. Add more icing sugar or milk until butter cream has a thick spreadable consistency. Finally stir in food colouring. Cover the side pieces of the cake with the butter cream.
Place the side pieces like flower petals around the centrepiece. Leave a little space between each petal and decorate with sprinkles and candy.