Steps

• The day before: prepare the base for the whipped cream! Heat the soy milk and pour it hot into your blender with the deodorized coconut oil. Blend for at least 2 minutes on maximum power. Let it rest in the fridge overnight.
• Prepare the sponge cakes: Take the zest from two mandarins. In a mixing bowl, combine the zest with the sugar, rubbing it well with your fingertips. Add the margarine and mix. Pour in the juice from the two mandarins, then the soy milk. Mix and add the flour, baking powder, baking soda, and vinegar. Whisk briefly to get a smooth batter. Pour this mixture into two sponge cake molds (mine are small with a diameter of 15 cm). Bake for 30 minutes at 180°C (355°F).
• Prepare the curd: squeeze the mandarins to get 100 mL of juice. Bring the juice to a boil with the margarine and about half of the soy milk in a saucepan. In a mixing bowl, whisk the sugar with the cornstarch, then gradually add the rest of the soy milk while whisking. Pour this mixture into the saucepan once the juice is boiling. Cook the curd for about 3 to 5 minutes over medium heat until it thickens, whisking continuously. Pour it into a dish to cool faster, and let it sit in the fridge for 1 to 2 hours until well set.
• Peel the remaining mandarins down to the flesh and separate the segments.
• Whip the cream prepared the day before into whipped cream, then fold in the powdered sugar, yogurt, vanilla, and a third of the clementine curd.
• For assembly: cut the sponges in half and soak them with a bit of mandarin juice. Place the first sponge on your serving dish, add a layer of whipped cream. In the center, place a big spoonful of curd and some fresh mandarin segments. Cover with a second layer of sponge and continue: whipped cream, in the center: curd and fresh mandarin, sponge, whipped cream... until the last sponge.
• Cover the entire outside of the cake with the leftover whipped cream. You can also pipe dollops of cream on top using a pastry bag. Decorate the cake with rosemary sprigs, sliced mandarins, and powdered sugar. It's ready! Enjoy within two days for the best results.