Ingredients

   
100g dark chocolate (60–70% cacao), chopped
42g unsalted butter, cubed
18g Dutch-process cocoa powder
90g whole milk (2% also works)
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 or cocoa powder 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 — keep water and steam out of the mixture.

  3. Add cocoa powder and stir until no lumps remain. Gradually stir in milk 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 or cocoa powder. Microwave chilled slices for 5 seconds for a melt-in-your-mouth texture.

Notes

  • The extra milk (90g vs the original 60g) compensates for cocoa powder absorbing more liquid than matcha. This keeps the fudgy, molten interior texture.
  • To intensify chocolate flavor without affecting texture, add 1–2g espresso powder to the batter with the cocoa. It deepens chocolate notes without tasting like coffee.
  • If you want more cocoa (up to 25g), add an extra 7g milk per 7g additional cocoa to maintain hydration — cocoa absorbs up to 100% of its weight in water.
  • Use Dutch-process cocoa for a smoother, less acidic flavor. Note that Dutch-process absorbs even more liquid than natural cocoa.
  • Use good quality dark chocolate (60–70% cacao), not chocolate chips — chips have stabilizers that affect melting.
  • The inside is intentionally soft and fudgy — don’t overbake.
  • Requires 4 hours cooling time before cutting.
  • Optional ganache topping: heat 80g heavy cream to a simmer, pour over 80g chopped dark chocolate, let sit 1 minute, stir until smooth, add 14g butter. Cool until pourable, then pour over the unmolded cake.
  • 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.