Any good, foolproof Christmas cake recipes? (preferably to fit a 10in square tin)

[NannyR]

I've bought the silverdale multisize tin (and some extra dividers) and instead of doing one large round cake this year, I want to do four 5in square cakes.

I've found loads of recipes online but each one seems to specify a certain size (usually round) tin. Does anyone have a recipe that would fit my 10in tin or alternatively, is there a formula to sizing up existing recipes to fit different sized tins?
Thanks

NannyR, there is a recipe for a Traditional Fruit Cake in the pack, printed on the inside of the box.

I have a recipe that I think was written for people who bake rich fruit cakes for weddings and gives quantities for all sizes of cakes from 6" round = 5" square right up to 13" round = 12" square

For 10" square the quantities are as follows:
700g of currants
500g of sultanas
175g of raisins
175g of glacé cherries (halved)
175g of mixed peel
175g of mixed nuts
2 teaspoons of grated lemon rind
8 tablespoons of brandy
500g of plain flour
2 teaspoons of mixed spice
125g of ground almonds
425g of soft brown sugar
425g of butter (softened)
2 tablespoons of treacle
8 eggs

Soak the fruit, nuts and lemon rind overnight in the brandy (I use more than the recipe and leave it longer than overnight)
When you are ready to make the cake put all the rest of the ingredients in a bowl and beat together until well combined . Fold in the fruit mixture using a metal spoon. Turn into a prepared cake tin and bake in a 140C/275F/Gas Mark 1 oven. Test after 3 hours. (Sorry, old recipe written before fan ovens)

Cool in the tin before wrapping and storing. The cake can be fed additional brandy during storage.

I make this cake every year. This year I'm using amaretto to soak the fruit, just for a change. I also tinker with the type of fruit. I buy a bag of mixed fruit and then add just currants and raisins until I reach the right total weight as I'm not a fan of cherries or nuts in cakes.

Thanks for the suggestions.