Recipe for an 11'; square sponge cake?

So Im making a cake for a friend the above size. A recipe I have in my book says I should use 13 eggs!!! The sponge is then baked and sliced in half to be filled with buttercreama and jam. This seems an awful lot of eggs!?? Plus my tin (Wilton) is only 2'; deep so surely when I level the cake off and fill it it is not going to be very high??





Any tips anyone?Recipe for an 11'; square sponge cake?
A cake that i always love is





50g of butter and sugar per egg


so 2 eggs 100g butter / sugar


then 100g flour per egg





Whisk butter and sugar untill light and fluffy


Slowly add in ur eggs whisking at each stage


Fold in half the flour untill completely mixed


Fold in the other half


Place in ur 11'; square tin place in oven on medium heat for 10 mins turn 10 mins turn


Ways to check wether cooked is it will be hard but bouncy upon touch or place a knife in the middle if it comes out clean the cake is cooked, if its dirty then place cake back in oven





You can modify this anyway you want add in some coco powder for chocolate, chocolate chips for well u know


you could cut it in half length ways and add in thick cream and jam to create a victoria sponge, hope this helpsRecipe for an 11'; square sponge cake?
13 eggs is around normal... give or take between different recipes...i use 12 when i make mine so its not a big difference.





Cooking time 1 to 2 hours





Ingredients


large sponge:


700g/1陆lb butter


700g/1陆lb caster sugar


12 medium eggs


700g/1陆lb self-raising flour


Directions


1. Preheat the oven to 180C/350F


2. Lightly butter and line the base of an 26cm/11in cake tin with greaseproof paper.


3. Cream the butter and sugar until smooth and pale in colour and then gradually beat in the eggs.


4. Sift the flour and fold into the mixture, a little at a time. Pour into the cake tin, level off the mixture with a palette knife and bake for about 90 minutes or until a skewer inserted into the cake comes out clean.