chocolate birthday cake help

[twocathedrals]

I need to make a chocolate birthday cake (why, oh why did I ask what she wanted?!) big enough to feed 10 adults and 5 children. Any recipe/size suggestions? I have one 20cm springform and one 23cm square tin but I'm prepared to buy more! I'm imagining something covered in chocolate icing and decorated with smarties. Help!

For 20cm I would use 3 eggs but divide between 2 tins.

My fav recipe is
3 eggs
180g castor sugar
180g butter
180g plain flour
3 tsp baking powder
180g plain chocolate, melted

I make it as for a standard sandwich cake adding the chocolate before the egg yolks, except I separate the eggs, whisking the whites until stiff and then fold them in with the flour. The extra baking powder (normally 3/4 tsp per egg is to compensate for the extra weight of the chocolate).

I sandwich it together with lemon curd (home-made) and ice it with the following

150g plain chocolate melted with 65g butter.
Might need double the quantity, depending how thick you want it, and how big the cake.

This can be either allowed to cool a little and then poured over the cake, or whisked until about milk chocolate in colour and then trowelled on, like a frosting. As dd once picked great holes in a cake covered with it, it is now known as 'picky cake icing' here.

Liking the ganache-style icing! And I love a recipe which uses chocolate instead of cocoa. Bit nervous about cake size, though... Is 20cm going to be big enough? I suppose I could just provide other sweet things and be stingy with the slices!

Have you got a ring cake tin? I've found them a bit easier to cut into lots of pieces. It would work in a square tin - keep the outside pieces for the grown ups, stop all the dc getting completely covered in chocolate.

A ring! Smart! Yes, I do in fact have a ring tin. You, tb, are a lady and a scholar!

Goodness! thank you tc. Depending on size, might need to go up to 4 eggs. If you have too much mixture you can always make fairy cakes with it.

Mmmm... I might deliberately make a huge a vat of cake batter to make fairy cakes inevitable...

You are wicked. Just thought of retro choc butterfly cakes with a good dollop of lemon curd instead of buttercream.

this is lovely.
It's super rich so you can't eat alot (very odd for me) and I leave out the coffee element.

M&S chocolate fudge cake packet mix x 2, might also surprise you.
I don't buy cake mixes but this was for an emergency and it tastes amazing and looks just like the ones on their shelves.

I forgot that I add nutella to my cake mix to make it gooey.

I use a very lazy recipe for chocolate cake that always turns out well

Weigh your eggs (3 or 4) and use that weight to measure out your butter and sugar and flour. Add in 25g very good chocolate powder (green and blacks is often cheaper than cadbury's)

A drop of water or milk may be needed if the mixture is a little dry. Oh, and always use proper butter and Nice eggs (as if you'd do anything else )