How about a Zebra cake. One batter/dough, that is divided into two equal portions, one of which is mixed with cocoa, then one drops a tablespoonful of dark mix into the centre of a round tin, then a spoonful of white on top of it, a spoonful of dark on top, then white and so on. Each new spoonful pushes the lower stratas further towards the edge. Don't stir, just keep adding batter until there is none left. Then bake the cake and top with an icing of rum and icing sugar. Make it a bit on the liquid side so it can soak into the cake. No artistry needed, but it will look and taste great. Not my picture, but it will give you an idea.
It travels well and is best made a day ahead.Zebra-cake - Zebrakuchen
5 egg yolks
250 g sugar
1 sachet vanilla sugar (=10 g of normal sugar and some v.essence)
rum flavour to taste
1/8 l lukewarm water
1/4 l oil (sunflower or some other neutral stuff)
375 g flour
1 satchet baking powder (15 g or two level tablespoons)
5 egg whites
2 tablespoons cocoa-powder
decorate with a runny rum icing
Whisk egg yolks, sugar and vanilla sugar with the mixer until creamy.
Add rum flavour, water and oil. Mix flour and baking powder and add this in stages.
Whisk egg whites until stiff and add them carefully to the dough. (make sure the whisk and bowl are absolutely fat free and no yolk has contaminated the egg whites)
Add cocoa-powder to one half of the dough, leave the other "white".
Butter a 26 cm round springform and cover with breadcrumbs.
Drop 2 tablespoonfuls of white dough right into the middle of the form, do not spread the dough.
Now drop 2 tablespoons of dark dough on top of the white, again without spreading.
Alternate 2 spoonfuls of each white and dark dough until the dough is used up. The dough will spread itself and if you want the zebra-pattern do not stir or spread the dough.
Baking: 40-60 minutes (upper and lower heat) at 170°C - 200°C (preheated)