Ok - this is for a big cake that you'd bake in a roasting tin, or some round cake tins (shallow):
12 eggs, separated (told you it was big! Serves 15 - or more 1 yr olds)
350g sugar (that do you, Mamazon?)
200g plain flour
100g cocoa powder
175g unsalted butter, melted and cooled.
Oven GM 4/180C/350F. Line tin(s) with baking parchment.
Whish egg yolks and sugar until thick and creamy - should leave a trail in the mix when you lift the whisk. Whisk egg whites together until light and fluffy. Sift cocoa and flour together, and fold into the sugar mix alternately with the egg whites and the butter.
Pour into tins and bake for about 35 mins for a deep cake, 20 mins for a shallow one, and 5-10 mins for a roasting tin. Check whether a skewer comes out clean.
Leavce in tin for a few mins, then turn out onto a wire rack to cool before removing paper.
Prepare large serving tray - cover with foil. Put cake on a board and cut it to desired shape - you can stick bits together with the topping. Assemble shape on tray. Ice it with chosen topping and then put fruit on according to your artistic whim.
Topping - thick greek yoghurt mixed with fruit puree; chocolate spread; nutella; 100g bars of chocolate mixed with 1 tsp double cream per bar (can also use caramel chcolate)
Doggie - I reckon you could use a vegan cake recipe and adapt. Might want to practice with a small one first.