For the coconut génoise:
Preheat the oven to 375°F.
Separate the egg yolks from the whites.
In a mixing bowl, beat the egg yolks with 3 tablespoons of granulated sugar until you get a pale, yellow foam; the texture of the egg yolk will be thicker. Add the vanilla and coconut extracts.
In a separate bowl, combine the flour, potato flour and baking powder. Sift the dry ingredients.
Combine the egg yolk mixture, dry ingredients, milk, oil and 2 teaspoons of coconut flakes.
In another bowl, add salt to the egg whites and whisk for about 2 minutes at a low speed. Add cream of tartar and the rest of the granulated sugar, increase the speed of your mixer and keep beating for another 2-3 minutes until it forms soft peaks. Don't over-beat or the texture will become grainy.
Using a silicone spatula, mix 1/3 of the whipped egg whites with the egg yolk mixture to soften it. Add the rest of the whipped egg whites and gently in fold in the eggs to get an airy batter.
Apply a thin layer of butter (approximately 1 tablespoon total) to a (12 x 17-inch) baking sheet, previously line with parchment paper. Pour the génoise batter; even it out using a spreader. Bake for 5 minutes at 375°F; lower the temperature to 350°F and bake for another 5-7 minutes. The texture of the génoise should be very soft.
Allow to cool for about 15 minutes. Cover the génoise with another piece of parchment (make sure it's much larger than the size of the baking sheet), place another baking sheet or flat board on top and flip the cake. Remove the still-warm baking sheet, gently remove and discard the old parchment paper and replace it with a large kitchen towel. Roll the cake with the towel and form a log. Let the cake cool completely (while preparing the ganache).
For the mango and rum ganache:
In another bowl, heat the heavy cream in a saucepan. Bring it to a near boil. Turn off the heat immediately and quickly add the finely chopped white chocolate. Stir until everything is melted. Add the mango extract and 2 teaspoons of rum extract. Let the mixture cool completely. Once cooled, whip the cream (at a low speed) until creamy and smooth for 2-3 minutes. Add 3 tablespoons of mango pulp. Stir well. Chill in the refrigerator for about 30 minutes.
For the roulade (génoise + ganache):
Unroll the cake and remove the kitchen towel. Using a spreader, spread the mango and rum ganache onto the génoise cake, stopping 2 inches before the end of the rectangle (the ganache will spread eventually until the end). Drizzle uniformly 5 tablespoons of mango pulp over the ganache and start rolling the cake, by lifting the parchment paper underneath the cake (as a guide). Form a log. Wrap the log with the parchment paper and chill in the refrigerator for at least 2-3 hours.
For the chocolate rum butter-cream:
In a bowl, sift the powdered sugar with the cocoa powder.
For the semi-sweet chocolate, place a pot filled with hot water (at a gentle simmer), topped with a piece of cloth so the bowl does not move and place a stainless-steel bowl filled with the chocolate chips on top. Stir until melted. Turn off the heat. Another option is to heat the chocolate for 20-30 seconds in the microwave. Watch the chocolate carefully; it could burn easily in the microwave!
In a separate bowl, cream the butter with the cocoa sugar mixture. Add the melted chocolate and the remaining rum extract (1 teaspoon).
For the rest of the coconut flakes:
Lightly dry toast the coconut flakes in a small skillet over medium high heat until slighted golden. You have to be very careful; otherwise the coconut could burn easily. Transfer to a plate. Allow to cool completely.
Un-wrap the parchment paper from the log, leaving the paper beneath the cake. Trim about 1 inch on each side of the log and discard the trimmings (we ate them!).
Cover the Yule Log with the chocolate butter-cream and smooth it out using a spreader. Using a fork, score lines along the length of the log, imitating the texture of wood. Cut 1-½" thick slice on the bias and place it on top of the log as a garnish. Sprinkle with the coconut flakes. Chill in the refrigerator for another hour.
Line up the serving plates. Place about 2 tablespoons of the mango pulp at the bottom of each plate. Place one slice of cake over the mango sauce. Repeat with the rest of the plates.
Depending on the measurement of your baking sheet, make sure not to over-fill the cake with ganache. When spreading the ganache, make sure not to spread too much at the edges of the cake so it doesn't burst on the side when rolled.
When you start to roll the cake, it's essential to roll it tightly so you don't have any air gap when serving the roulade.
I prefer using canned mango pulp because the mangoes are picked at the peak of ripeness, which guarantees a consistent result. I get it at the Indian store but you can also get it online. I prefer the Kesar mango variety, which is much smaller than the Alphonso kind and much sweeter.
You can also use a fresh ripe mango if you don't have canned mango pulp. You might check the level of sweetness though.
Similar to other cake recipes, I use potato flour for a lighter, fluffier result.
Sifting dry ingredients helps to get rid of lumps of flour and also to aerate the mixture when liquid is added. It's very important for all of your baking so you get a moist result.
To ensure that the log doesn't crack, roll the génoise in a kitchen towel while it's still warm.
For more Christmas desserts, click on the link.