Preheat the oven to 180 C / Gas 4. Grease a 23x33cm (9x13 in) baking tin.
Cream together the butter and sugar. Beat in the eggs, cocoa, vanilla, cinnamon and cloves. Once smooth, add the flour and milk alternately, stirring till a smooth. Stir in the currants or sultanas. Finally, dissolve the bicarb in a spoonful of boiling water from the kettle, then add to the cake mixture. Tip the mixture into the prepared tin.
Bake in the preheated oven for 30 to 35 minutes, or till a skewer inserted in the centre comes out clean.
Once cool, cut cake into slices and serve.
Use whatever you have in the cupboard! Instead of currants you could use chocolate chips, chopped nuts, or a combination.
You can bake in a smaller cake tin for a less shallow cake; simply fill the tin no more that 2/3 full and adjust baking time as needed.
If you don't have soured milk, make your own by adding 2 teaspoons of lemon juice or vinegar to regular milk and letting it sit for 5 minutes before using in the recipe.