In a food processor combine almonds and rolled oats. Process at high speed for 1-2 minutes, until the mixture resembles fine dust or sand (skip this step if you are using oat flour and almond meal).
Transfer the mixture to a large bowl. Add baking powder, baking soda and salt and whisk well. Add also the spices, chia seeds and xylitol and stir again until combined.
Add the eggs and whisk. The mixture will become very thick and sticky. Add the oil and whisk again. At the end add the clementine juice, little by little, to create a batter. Don't add the whole quantity if you notice that the batter becomes too thin (or you may need to add more if it is still too thick).
Preheat the oven to 350ºF/ 180ºC.
Grease very well a 7 inch/ 18 cm cake pan and line it with a circle of parchment paper.
Transfer the batter to the prepared pan. Bake for about 35 minutes or until a toothpick inserted in the centre comes out clean.
Let the cake cool until room temperature before serving it. Decorate with whole tangerines and sprinkle with powdered xylitol.
The recipe works with both ground almonds and oats and with the respective flours. The reason you may want to prepare the mixture at home is to ensure better quality. However in a food processor the consistency will not be as fine as the store-bought flours. That is still ok, just keep in mind that the coarse consistency will make the texture of your cake crumblier.
You may need a bit less or more than 1 clementine for this recipe, depending on its size and on the other ingredients.
This cake will not have a clementine flavour if using just the juice. If you really want the specific fruit taste, you can add clementine extract.
Keep this cake for 3-4 days refrigerated and covered with plastic wrap or in airtight containers.