Go Back
Dark Chocolate Prune Cake with Passionfruit Curd

Dark Chocolate Prune Cake with Passionfruit Curd

This rich Dark Chocolate Prune Cake is a fudgy, flourless cake made with Armagnac-soaked prunes and topped with Swiss meringue buttercream and a tart Passionfruit Curd.
Print Recipe Pin Recipe
Prep Time 45 minutes
Cook Time 1 hour
Cooling Time 4 hours
Servings: 8
Course: Dessert
Cuisine: French
Ingredients Equipment Method Notes

Ingredients
  

Pruneaux à l'armagnac 
  • 2 bags black tea I used Ceylon
  • 2 cups boiling water
  • 250 g (9 oz) pitted prunes
  • 1 1/2 cups Armagnac
Dark Chocolate Prune Cake
  • 340 g (12 oz) dark chocolate chopped
  • 12 tbsp unsalted butter cut into cubes
  • 4 tbsp granulated sugar divided
  • 6 large eggs separated
  • ¼ tsp sea salt
  • ⅛ tsp cream of tartar
  • Cocoa powder for dusting
Passion Fruit Curd
  • 8 passion fruits
  • 1 lemon zested and juiced
  • ½ cup granulated sugar
  • 2 large eggs
  • 2 large egg yolks
  • 4 tbsp unsalted butter cold and cut into cubes
Swiss Meringue Butter Cream
  • 1 vanilla bean split lengthwise
  • 3 large egg whites
  • 3/4 cup granulated sugar
  • ¼ tsp sea salt
  • ⅛ tsp cream of tartar
  • 1 cup unsalted butter softened but not warm, cut into cubes

Equipment

  • 1 large resealable jar
  • 1 small saucepan
  • 1 heatproof bowl
  • 1 blender or smoothie cup
  • 1 Hand or Standmixer
  • 1 9" springform pan
  • 1 small fine mesh sieve
  • 1 sultan piping tip

Method
 

For the Prunes
  1. Place the tea bags in a large resealable jar, then cover them with boiling water. Let steep for 5 minutes. Remove and discard the bags. Add the prunes to the tea and let sit for 4-12 hours.
  2. Drain the prunes and cover them with the Armagnac. Seal the jar and let them soak for at least 48 hours, up to a week.**
For the Cake
  1. Preheat the oven to 325°F. Grease a 9" springform pan with butter and dust the interior thoroughly with cocoa powder. Set the pan to the side.
  2. Place the butter and chocolate in a heatproof bowl. Place the bowl over the mouth of a small saucepan with about 2 inches of gently simmering water. Slowly melt the chocolate and butter together until no lumps remain.
  3. While the chocolate and butter are melting, drain the prunes and place them in a blender, food processor, or smoothie cup. *** Add a tablespoon of the sugar and blitz until smooth.
  4. Add the prune purée to the chocolate mixture and whisk to combine. Add the egg yolks and, again, whisk to combine. Set the mixture aside.
  5. Pour the egg whites into a stand mixer or a large mixing bowl. Add the salt and cream of tartar and whip on high using a whisk attachment or a hand mixer. While whisking, slowly stream in the remaining 3 tablespoons of sugar.
  6. Fold 1/3 of the whipped egg whites into the chocolate mixture until no streaks remain. Repeat with the remaining egg whites. Pour the finished batter into the prepared pan and smooth the top.
  7. Bake the cake for 40-45 minutes. The cake should still jiggle in the middle. Transfer the cake to a cooling rack and let it cool for 20 minutes before removing the ring. The cake is very delicate while hot. Let cool completely. ****
For the Passion Fruit Curd
  1. Pour the sugar into a bowl and add the lemon zest. Rub the zest lightly into the sugar with your fingertips. Set the sugar to the side.
  2. Split the passionfruits in half and scrape out the pulp into a food processor. Pulse a few times to loosen the membrane around the seeds. Pour the passionfruit pulp into a fine-mesh strainer and use a spoon or a muddler to force as much juice out of the pulp as possible. You should have about 1/2 cup.
  3. Pour the passionfruit juice into a small saucepan. Add the lemon sugar, the eggs, the yolks, and the juice of the lemon you zested earlier. Whisk to combine and place over low heat.
  4. Cook the curd over low heat until it reaches 170-180°F. Pour the hot curd through a fine mesh strainer and immediately add the butter. Stir until the butter melts completely. Chill the curd for at least 3 hours.
For the Swiss Meringue Buttercream
  1. Take the vanilla bean and scrape out the caviar using the blunt end of a knife. Set the caviar to the side and store the pod for future use.
  2. Place egg whites, sugar, salt, and cream of tartar in a heatproof bowl. Place the bowl over a small saucepan with 2 inches of simmering water and cook gently while whisking constantly. Cook until the mixture reaches 185°F. This should take about 10 minutes.
  3. Take the egg whites off the heat and pour them and the vanilla caviar into a mixing bowl or the bowl of a stand mixer fitted with a whisk attachment. Whisk the egg whites on high (you can also use a hand mixer for this) until the mixture cools to 90°F.
  4. While still whipping, start adding the butter, roughly 1 tablespoon at a time. Whip until the rich and creamy frosting forms. It will look a little rough on the way to being perfect, so don't freak out.
To Assemble
  1. Transfer the Swiss Meringue Buttercream to a large piping bag fitted with a sultan tip. Pipe the frosting onto the surface of the room-temperature cake. **** Fill in the center of each frosting dollop with the passionfruit curd. Finish with shaved chocolate and serve immediately.

Notes

** Don't leave the prunes in the Armagnac for more than a week. They will be far too strong at that point. 
*** Don't throw out the Armagnac you used to soak the prunes in. You have inadvertently made prune-infused Armagnac, a delightful ingredient you can use in cocktails, glazes, sauces, and puddings. 
**** If you chill the cake in the fridge, bring it up to room temperature before piping the frosting onto the cake. If the cake is cold, this will solidify the butter in the buttercream, and it will not stick to the cake.