If you are using store bought marzipan you can move on to the next step. For a really good cake I recommend making half of my home-made marzipan recipe, you can find the recipe here. Pre-heat the oven to 180°C fan / 400°F / Gas 6.
Line a 20cm springform pan with baking paper.
In a large bowl or food processor add all the dry ingredients for the cake. Start mixing and finally add the liquids (egg, oil and vanilla). Continue mixing until you have a nice smooth batter.
Sprinkle some icing sugar on the worktop and roll out the marzipan into a circle, roughly the same size as the pan.
Spoon half the cake batter into the prepared pan and even out the top. Scatter over half of the prepared rhubarb.
Lay the marzipan on top of the cake batter in the cake pan then add the other half of the batter and even out the top.
Scatter over the remaining rhubarb and the flaked almonds.
Baking: Place the cake on the middle shelf and bake for 1 hour 20-30 minutes, covered with kitchen foil for the first 60 minutes. Test the cake to see if it has fully baked with a skewer or toothpick inserted into the centre. Be aware, a little marzipan may stick to the skewer meaning it doesn’t come out clean, even when the cake is fully baked through. Once baked, remove from the oven and leave to cool in the pan for about 30 minutes, then remove from the pan and transfer to a wire rack and allow to cool.
Once cooled dust with some icing sugar and serve.