Ingredients:

  • 250g all-purpose flour
  • 500g granulated sugar, divided
  • 75g Dutch-processed cocoa powder
  • 2 tsp baking soda
  • 1 tsp baking powder
  • 1 tsp fine sea salt
  • 2 large eggs, room temperature
  • 240ml full-fat buttermilk
  • 120ml neutral oil (avocado or vegetable)
  • Zest of 2 large organic oranges
  • 270ml fresh orange juice, divided
  • 120ml boiling water
  • 3 large egg yolks
  • 1 tbsp cornstarch
  • 50g unsalted butter, cubed
  • 300g dark chocolate (60% cacao), finely chopped
  • 300ml heavy whipping cream
  • 1 tsp orange extract

Instructions:

  1. Preheat oven to 350°F (175°C). Line three 8-inch round cake pans with parchment paper.
  2. In a large bowl, massage the orange zest into 375g of granulated sugar until fragrant. Whisk in flour, cocoa, baking soda, baking powder, and salt.
  3. Add eggs, buttermilk, oil, and 150ml orange juice. Whisk until combined. Slowly stream in boiling water while whisking until the batter is thin and smooth.
  4. Divide batter between pans and bake for 35 minutes, or until a skewer inserted comes out clean. Cool completely.
  5. Prepare curd: Whisk 120ml orange juice, 125g sugar, 3 egg yolks, and cornstarch in a saucepan over medium heat until thickened. Stir in butter and zest, then chill.
  6. Prepare ganache: Heat heavy cream until simmering, pour over chopped chocolate. Let sit for 5 minutes, then emulsify. Add 1 tsp orange extract and whisk until the ganache is thick enough to hold a soft peak.
  7. Assemble: Place one sponge layer, pipe a 'ring' of ganache around the edge, fill with half the curd, and repeat. Frost the exterior with the remaining ganache until the cake is fully sealed and smooth.