chocolate, mandarin & thai basil roll cake

I will miss you citrus season! To fondly express my undying adoration, here is one last ode to citrus for this winter, in the form of a chocolate roll cake filled with Thai basil-infused whipped ganache and whole mandarins.

This cake was inspired by pictures I’ve seen of roll cakes harbouring whole oranges or mandarins, such as at Mari Bakery. Here I’ve used mandarins, perfectly scaled to fit my small batch roll cake preferences. It’s rather showy (so long as you cut the cake in the right place) and a little tricky to eat, but also likely the most efficient way to pack as much fresh orange as possible into a cake.

The flavours I’ve used are analogous to the combination of chocolate, mint and orange, with Thai basil bringing menthol and an added herbaceousness.

• Servings: about 6
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Cake adapted from Rice n’ Flour. Whipped ganache proportions based on Duchess At Home by Giselle Courteau. Concept inspired by images I’ve seen of whole orange roll cakes.

whipped thai basil & dark chocolate ganache

• 205g heavy cream, divided
• 15g thai basil leaves, coarsely chopped
• 65g dark chocolate (what you use will determine the sweetness – use 70% for a more typical sweetness, I like 85% for a more muted sweetness)
• small pinch salt

chocolate cake

• 45g boiling water
• 15g cocoa powder
• 30g oil
• 3 eggs, divided
• pinch salt
• 30g flour
• 45g sugar
• pinch cream of tartar, optional

assembly

• about 5 small (~5.5cm in diameter) mandarin oranges, peeled (the number needed will depend on size)

thai basil & dark chocolate whipped ganache

Heat 150g of the cream until steaming (but not boiling) and pour over the chopped thai basil leaves. Cover, set aside to cool, then place in the fridge to finish infusing for at least three hours or overnight. Press the cream through a sieve to extract about 135g of cream.

Chop the dark chocolate and place in a heatproof bowl. Heat the cream until scalded (nearly boiling) and pour overtop of the chocolate. Leave for a few minutes to begin to melt, then whisk until smooth. Now whisk in the remaining 55g of the cream.

Cover and chill the ganache completely. You can leave it in the fridge until you’re ready to assemble the cake. Whip just before using.

chocolate cake

Preheat the oven to 350F. Line a quarter sheet pan (9×13″) with parchment paper.

In a medium-large mixing bowl, whisk together the cocoa powder and boiling water until smooth. Let cool and then add the oil, 3 egg yolks and salt. Whisk until smooth. Finally, sift the flour over top and whisk until smooth.

Meanwhile, place the 3 egg whites in the bowl of a stand mixer. Beat until frothy with the whisk attachment, then sprinkle in the sugar and cream of tartar. Whip until stiff peaks are formed. Whisk one dollop of the egg whites into the egg yolk mixture. Then switch to a rubber spatula and fold in the remainder.

Scrape into the prepared pan and use an offset spatula to spread the batter into all the corners and into an even layer. Bake about 15 minutes or until a skewer inserted into the centre is removed clean. Let cool completely.

assembly

Use a whisk to whip the ganache until it resemble whipped cream. Spread about 3/4 of the whipped ganache on the cake, sparing one strip along the short edge furthest from you.

Line up the mandarins (reference the above pictures if needed) along the edge of the cake closest to you, nestling them into the whipped ganache. Use a small offset spatula to spread the remaining ganache on the mandarins, filling in any spaces until the mandarins resemble a cylinder.

Now roll up the cake, starting from the edge closest to you, enclosing the mandarins. Cover in plastic and chill at least an hour to allow the ganache to firm up.

When ready to serve, garnish with whipped cream, mandarin segments and thai basil leaves. Slice using a serrated knife.