A wonderful, gluten-free, moist cake.
Remove stem nub from clementines and lightly rinse them. Put clementines into a large pot and fill it with cold water. Cover and bring it to a boil. Keep it at a slow boiled for 2 hour. Watch that you don't lose too much water, the clementines should always be floating. Drain and let cool.
In a blender, blend the whole boiled clementines (rinds and all). Put them in one at a time. Add the 6 eggs while blending on high.
I then move the clementine and egg mixture to a large stand mixer. I then slowly add the ground almonds. Then the sugar and finally the baking powder.
Butter and line an 8-inch spring-form pan with parchment paper. Pour the cake mixture into the prepared pan and bake for 40 minutes at 375. Then cover the pan with foil and bake for another 20 minutes or until a skewer will come out clean. Remove pan from oven and leave to cool, in the pan, on a cooling rack. When the cake is cold you can take it out of the pan.
Best served a day or two after baking. The flavors continue to build over the next 24-36 hours.
I like making my own ground almonds from lightly roasted (unsalted) whole almonds. They tend to taste better and I can control the consistency. What I do is to first do a medium grind before moving 3/4 of the ground almonds to my high speed blender. I use it to very finely grind the almonds, creating a near paste like consistency. This give the cake some texture along with a very fine distribution of the almond flavor.
Be careful with this process as the almonds have a reasonable amount of oils that will make the finely ground almonds clump. One time I tried using a coffee grinder but that did not work out very well. The blender continues to work out the best.
I have found that it is actually easiest to get the 16-ounce package of Almond Meal from Trader Joe's as that saves a lot of time and fuss. The texture of the cake is not quite as interesting as almond meal is more consistent in granularity but the cake tastes just as good and it saves a lot of time and fuss.