• Place the whole clementines in a saucepan with a lid. Cover them with an inch of water and bring to a boil. Cover and let the mandarins continue to simmer on low heat for two hours until the entire fruit is very soft and pulpy.
• Preheat the oven to 350 degrees Fahrenheit.
• Once the fruit has cooled, discard the water they were cooked in and remove seeds from the fruit, if any. Place the mandarins in a food processor and process into a coarse puree.
• Add all of the remaining ingredients for the cake into the food processor. You can also do this in a bowl. Mix everything until well incorporated.
• Spray a 9-inch cake pan with cooking spray or brush with oil. Line the bottom with parchment paper. A springform pan, is preferred, if you have one but you can use a regular cake pan.
• Scrape out the batter into the cake pan and smooth the top, if necessary, with a spatula.
• Place the cake in the oven and bake an hour or until a toothpick in the center comes out clean.
• Place the cake pan on a rack and let it cool about 30 minutes, then carefully unmold the cake, peel out the parchment paper, and continue cooling it on the rack.

Make the candied clementines

• Place the sugar, water and cardamom in a saucepan and bring it all to a boil.
• Add the thinly sliced clementines, bring to a boil, lower heat to a simmer, and cover and cook for an hour. You can place a piece of parchment paper directly on the sugar syrup to keep the clementine slices immersed, then cover with the lid.
• Once the clementine slices have cooled, use them to decorate the clementine cake.