Place mandarine in saucepan, add water to cover. Bring to boil, and cook for 2 minutes. Put a lid on and let sit over night. Drain ans rinse mandarines . Cut off stem, quarter and discard seeds and any tough membranes left. In a food processor give a few pulses, and add sugar and pectin and gently puree. Transfer orange mixture into a saucepan, bring to a boil and cook for 5 minutes. Cool and keep refrigerated for weeks. Spread 7 oz/200g onto plastic wrap sheets, form a cylinder and freeze to sit.
Bring to boil, water, sugar and orange zest. Cool and add orange blossom water to taste. Use at room temp or slightly warm.
Turn oven on. Whisk eggs, yolks and sugar over a water-bath until the mixture gets warm. Beat on high speed for 8 min until light and fluffy. Fold in sifted powders and spread mixture onto a lightly oiled baking mat or parchment paper into a 12x18''/30x45cm ≈ 1/2''/1.5cm thick sheet.
Bake at 425ºF/220ºC for about 7 min or until just baked. Cool 10 min – flip biscuit over a greased or lightly sugared parchment layered on a kitchen towel and roll; store at room temp.
Melt chocolate over a water-bath (just melted). Soak gelatin sheet in cold water to soften; drain. Whip heavy cream to soft peaks; chill. Make a crème Anglaise: bring milk to boil with one-third of the sugar on medium heat. Meanwhile, beat yolks and remaining sugar. Pour hot milk into the yolk mixture gradually and whisk well. Return to stove and cook custard to 185ºF/85ºC on low heat, stirring constantly. Do not boil. Remove from the heat, whisk in the melted gelatin and pass through a sieve over the melted dark chocolate; mix well. When the chocolate mixture reaches 100ºF/38ºC, fold in whipped cream.
Melt chocolate – heat up cream and milk, mix in chocolate powder and add melted chocolate. Blend without incorporation air. Use at ≈ 104 ºF/40ºC.
Arrange chocolate sponge skin side up onto a couple of sheets of plastic wrap. Moisturize biscuit with some orange syrup and spread 1 lb./450g chocolate mousse. Place the frozen mandarine marmalade cylinder on the bottom end; roll into log and freeze for a couple of hours. Cover the log with the remaining mousse and place in the freezer overnight and glaze the log. For the knots, slice out ends into 1''/2.5cm cuts and place on the log – use some of the leftover glaze to seal it. Decorate* and serve thawed. Merry Xmas!🎅🏻*Decorations used in the videos are chocolate shavings, nougat de Montelimar cubes (Look up recipes) and French meringue mushrooms.