Preheat the oven to 180°C (350°F) Gas 4. Mix together the milk and vinegar in a bowl and set aside for 10 minutes.
Sift the unbleached flour, bicarbonate of/baking soda, baking powder, cocoa and salt into a mixing bowl, then add the wholemeal/whole-wheat flour and cinnamon and mix well.
Add the syrup (see TIP below), oil and zest to the vinegar mixture and mix well. Gently fold these into the dry ingredients with a spatula. Make sure not to mix too much, otherwise the cake might turn chewy. When everything is just incorporated, spoon the mixture into the prepared cake pan and spread evenly with the spatula.
Bake in the preheated oven for 20–25 minutes or until a skewer inserted in the middle comes out clean. Spring open the cake pan and allow the cake to cool completely. When the cake is cold, peel off the paper. Slice the cake in half horizontally with a large, serrated knife. You can also cut off the top if it has domed while baking and you prefer it to be flat.
Put the jam and rum or juice in a small saucepan and heat until it comes to the boil. Spread this over both cake layers – this will make the cake moist and stop any frosting from seeping into the cake. Allow to cool. Put the lower cake layer back in the cake pan and attach the springform ring. The cake is now ready to be topped or filled.
TIP: If you are serving the cake as it is (without a filling or frosting), add a little extra syrup to the mixture, or spread something sweet over the cake after baking.
Excerpted with permission from <a target="_blank" href="https://www.amazon.com/gp/product/1849758638/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1849758638&linkCode=as2&tag=craftfocom-20&linkId=951a1d44952706512f13d539b4f25e7b">The Vegan Baker: More than 50 delicious recipes for vegan-friendly cakes, cookies, bars and other baked treats</a>.