I made my old favourite Coffee Battenberg for a friend's tea and cake afternoon today. I say old favourite, but I haven't actually blogged it before even though I've made it at least three times and had various rave reviews!
[2016 update: I've added a method variation for a non-coffee version, at the bottom.]
It's a basic 6oz sponge mix, half left plain and half mixed with cocoa and coffee, baked in two loaf tins and then trimmed and cut into bars. Sandwich with coffee buttercream and wrap in marzipan... job done.
Of course, the reality is a bit trickier, but it's still not too hard to make.
175g butter, softened
175g caster sugar
3 large eggs, lightly beaten
175g self raising flour
1tsp baking powder
1tbsp cocoa powder
Half of: 1 tbsp coffee granules dissolved in 2 tbsp boiling water and cooled
1 tbsp milk
200g icing sugar, well sifted
Other half of the coffee mixture
400g white marzipan
Oven to 180°C / 160°C fan, grease and line 2 loaf tins (note - the more crisply you can line the tins, especially at the corners, the less cake edge you will have to trim!). You could use silicone pans, which don't need lining but tend to have softer corners. Or, take the Great British Bake Off/Mary Berry tactic of making a greaseproof divider in a square tin, but make sure it's at exactly halfway. A divided square tin will need more cooking time.
Cream butter and caster sugar until fluffy. Add eggs gradually and beat well after each addition. Sift in flour and baking powder and beat well. Divide the mixture in half as accurately as you can (this is important - weigh if you have to), and add the cocoa and the (half) coffee mixture to one half, mixing well before spooning it into the tin. The plain mix has the tbsp of milk beaten in (to keep the texture the same as the coffee one) and goes in the other tin. When levelling the mixture, leave a generous dent in the centre to allow for more rising there. Bake for 30-35 minutes (45+ for a square tin) until springy in the middle / a skewer comes out clean; test both cakes! Cool in the tin for 5 minutes and then on a rack.
Beat the butter, icing sugar and coffee mixture until smooth, and set aside. Roll the marzipan out to pound coin thickness, at least as wide as your loaf tins are long and four times as long as your loaf tins are wide (at the bottom) - leave a safety margin for trimming. A silicon pastry mat is really helpful here. Use icing sugar to prevent it sticking, and keep flipping and turning it as you roll. Crucially, make sure it is not stuck to your surface before you start constructing!
When the cakes are cool, trim them as sparingly as you can, i.e. remove only what you need to make two evenly sized blocks with neat right-angle corners. Leave the ends until later, to trim them and the marzipan at the same time and get a neat finish. I do all of this trimming with a bread knife. Crucially, the cakes need to be the same height and width otherwise you'll have a wonky finished product. I have found that stacking 3 CD cases (you remember those...) each side of the cake gives me a way to trim the top nice and level without wasting too much, and then I stack the cakes on top of each other to trim the sides vertically and ensure they are the same. Finally, cut the two blocks in half lengthways to make two sticks of each flavour. I have to confess that I get a ruler out at this point!
To construct, take a bricklaying approach. A palette knife and a jug of hot water for warming it will make life easier. Spread buttercream on one side of one sponge and put it buttercream-down on the marzipan near one end (leaving a margin for final wrapping). Then spread more on the inner side of that sponge. Buttercream another (opposite colour!) sponge and place it icing-down next to the first, against the spread side. Spread the top of both these sponges together, add another sponge on top, spread its inner side, and add the final sponge to make the square. Now cover the three outer sides of the block with buttercream too and you're ready for marzipan.Overall, this is not your delicate afternoon tea Battenberg in this particular incarnation. It's pretty hefty! But it seems to hit the spot and it all disappeared at the tea and cake session... and every other time I have made it since.
Bring the marzipan over the cake, being careful not to tear it, and making sure the corners are not baggy. If you have a fondant icing smoother tool, it can help get everything flat. Leave the ends rough for now. Allow a centimetre or two for the overlap along one side, feather the edge that will lie on top (press it down to make it thinner), and moisten it with water to make it stick. Roll the cake over to put this on the bottom. Now trim the marzipan edges and the cake ends at the same time to get a clean, flat face, and pinch along the corners of the cake slightly to sharpen them. The trimming can be easier to do if you chill the cake first, to firm up the buttercream and marzipan.
Make the plain mixture as above. Rather than the coffee and cocoa, add a little red colouring and (optionally) rosewater to one half, and (optionally) almond essence to the other. Gel colour will give a nice shade without making the cake mix too sloppy. Sandwich with jam (sparingly) instead of buttercream - plum or seedless raspberry work well, apricot would also be fine. Wrap with yellow marzipan.