This cake is an all in one, which is one of my favourites as you put everything in, mix and hey presto.

Ingredients

200g caster sugar
200g butter, softened plus extra for greasing 
200g self-raising flour 
2 tbsps cocoa powder 
1 tsp baking powder 
4 large eggs 
1 tsp vanilla extract 
2 tbsp milk 

For the buttercream 
100g milk chocolate, chopped 
200g butter, softened 
400g icing sugar, sifted 
5 tbsp cocoa powder, sifted 
2 tbsp milk 

For decoration 
Marshmallows 
Ready rolled white fondant icing  
Black edible pen for the eyes - or icing eyes 
250g Biscoff biscuits

Equipment 
23cm square cake tin 

Method
Heat oven to 180c. Grease and line the base and sides of a square cake tin with baking parchment. 

In a stand mixer put all of the ingredients and mix until pale.  If you do not have a mixer you can use a hand held mixer or a wooden spoon. Scrape down the sides and remix.  Pour the mixture into the tin and bake for 20-25 minutes or until a skewer inserted into the middle of the cake comes out clean.   

Leave the cake to cool completely and don't take out of the tin for at least 15 mins in the tin.  Melt the chocolate by blasting for 30 seconds, stirring with a knife and repeating until all chocolate is melted.  By doing this in 30 second blasts, it stops the chocolate from burning.

Once the cake is completely cool, make the buttercream.  Put the butter and icing sugar into a stand mixer and slowly stir together until they are thoroughly mixed through.  Again, if you do not have a mixer you can use an electric hand held mixer or wooden spoon, just take it slowly at first.

Stir through the cocoa powder and then add the chocolate and milk.  Mix until completely mixed through and smooth.

You now have two options, you can cut the cake in half and buttercream the middle with half of the buttercream and put the other half on the top or you can just put all of buttercream on the outside.  Put the cake on a chopping board and then cover the cake with the buttercream.  Take some of the biscuits out of the packet and put them to one side and take the rest and crush over the top for soil.  If you have an edible pen write 'RIP' on the biscuits and then dig them into the top of the cake. 

To make the ghosts, put 2 marshmallows on top of each other, 'gluing' together with buttercream.  Unroll the icing and cut around a saucer - this the white 'sheet' of the ghost.  Put the sheet over the top of the marshmallows and draw eyes on your ghost.  Place your ghosts on your cake. 

This was a family affair, Matt and I baked and then I let him decorate. The thing about cooking and decorating cakes with kids is you can't be too pedantic about the decoration, you kind of have to let them do their thing and not worry about how it looks. For control freaks this might be difficult. I know this because that person is me.

- Original recipe from BBC Good Food