Boil the Clementine (5) for 2 hours. Drain and cool. If they have seeds, remove them. Vigorously mix the softened fruits together to until you have a thick paste.
Preheat oven to 375 degrees F (190 degrees C). Grease a 9-inch pan, and place a round piece of parchment paper on the bottom.
Line the perimeter of the pan with thin slices of Clementine (to taste).
Mix the clementine paste, Granulated Sugar (1 cup), Brown Sugar (1/2 cup) together until smooth.
Add the Egg (6), Almond Flour (2 1/3 cup), Unsweetened Cocoa Powder (1/3 cup), Vegetable Oil (2 tablespoon), and Baking Powder (1 teaspoon) and mix until uniform. Pour into the prepared pan and place in the oven on the middle rack.
Bake for about 40-50 minutes. Any time I've made this cake the baking time varies. Be sure to start checking for doneness at 40 minutes or earlier. If it looks like it's burning, cover with foil for the last few minutes. When I baked it in a cast-iron skillet it only took 30 minutes. It's done when it no longer has a jiggle in the center and is firm to the touch.
Cool in the pan for about 30 minutes. Remove from the pan by loosening the sides with a butter knife, placing a serving dish over the cake pan, and flipping the cake upside down onto the serving dish. Remove the parchment paper.
Sprinkle with Powdered Confectioners Sugar (to taste) and Chocolate Shavings (to taste).