Ingredients

   
100g dark chocolate (60–70% cacao), chopped
42g unsalted butter, cubed
18g Dutch-process cocoa powder
6–8g orange zest (1 large orange)
90g whole milk (2% also works)
10g Grand Marnier or Cointreau (optional)
3 large eggs (50g without shell), yolks and whites separated
38g sugar (for egg yolks)
20g cake flour
1g kosher salt
38g sugar (for egg whites)
  Confectioners’ sugar for dusting (optional)

Steps

  1. Preheat oven to 350°F. Line a 15cm round cake pan with parchment paper.

  2. Melt dark chocolate and butter in a double boiler (bowl over simmering water, not touching). Stir until smooth. Remove from heat.

  3. Add cocoa powder and orange zest, stir until no lumps remain. Gradually stir in milk and Grand Marnier (if using) until smooth.

  4. Refrigerate or freeze egg whites for 15 minutes until cold.

  5. In a large bowl, whisk egg yolks and 38g sugar vigorously until creamy and pale. Add the chocolate mixture and mix well.

  6. Sift 20g cake flour into the batter. Gently whisk until just incorporated — do not overmix. Add salt and stir.

  7. Whip cold egg whites on medium-low until bubbly and foamy. Gradually add 38g sugar while beating. Increase to high speed and beat until stiff, glossy peaks (about 2 minutes).

  8. Fold one-third of the meringue into the batter and mix well. Fold in another third gently. Add the last third and fold until just combined — don’t deflate the bubbles.

  9. Pour batter into the prepared pan and smooth the surface.

  10. Bake at 350°F for 15 minutes, then reduce to 325°F and bake 20 more minutes. The center will still wobble slightly — this is correct. Do not skewer-test this cake.

  11. Cool completely in the pan on a wire rack, about 4 hours. Can also refrigerate overnight.

  12. Dust with confectioners’ sugar. Microwave chilled slices for 5 seconds for a melt-in-your-mouth texture.

Notes

  • Orange zest adds flavor through oils, not water — zero hydration impact. The milk stays at 90g (same as the chocolate gateau) because the cocoa still needs the extra liquid.
  • Grand Marnier is optional but recommended. The 10g of liqueur replaces 10g of the milk’s role as liquid, so no adjustment needed. The alcohol mostly evaporates during baking, leaving behind concentrated orange flavor.
  • Use a microplane for the zest — you want the orange oils, not the bitter white pith.
  • Use Dutch-process cocoa for a smoother, less acidic flavor that pairs well with orange.
  • The inside is intentionally soft and fudgy — don’t overbake.
  • Requires 4 hours cooling time before cutting.
  • Cake flour is required. Homemade: for every 120g AP flour, remove 16g and replace with 16g cornstarch, sifted 3–4 times.
  • Double the recipe for a 20–23cm pan, triple for 25–28cm.
  • Store refrigerated 3 days or frozen 1 month.