Ingredients

   
100g white chocolate (baking quality), chopped
42g unsalted butter
1 vanilla bean (seeds scraped) or 5g vanilla bean paste
55g whole milk (2% also works)
3 large eggs (50g without shell), yolks and whites separated
38g sugar (for egg yolks)
32g 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. Brown the butter: melt butter in a small saucepan over medium heat, swirling occasionally, until the milk solids turn golden-brown and it smells nutty (about 5 minutes). Pour into the bowl with the white chocolate — the residual heat will help melt it. Stir until smooth. If needed, set briefly over the double boiler to finish melting.

  3. Add vanilla bean seeds (or paste) to the melted chocolate mixture and stir well. Gradually stir in milk.

  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 yellow. Add the vanilla chocolate mixture and mix well.

  6. Sift 32g 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

  • Browning the butter is what makes this recipe work. Plain vanilla + white chocolate is too subtle on its own — the browned milk solids add nutty, caramelized depth that gives the cake an actual flavor identity. Don’t skip this step.
  • Milk is reduced from 60g to 55g and cake flour is increased from 20g to 32g to compensate for removing 18g of matcha. Matcha barely absorbs liquid, but it contributes bulk and body to the batter. Without replacing that volume, the batter is too thin and the cake won’t set properly. Flour absorbs more liquid than matcha (~60% vs ~15%), so we use 12g extra flour (not the full 18g) and reduce milk by 5g to keep the wet-dry balance right.
  • Use real vanilla bean or vanilla bean paste, not extract. Extract is mostly alcohol which evaporates during baking, leaving weak flavor. Bean paste or seeds infuse directly into the white chocolate and fat, which carry flavor much better.
  • If using vanilla extract as a last resort, use 10g and add it to the egg yolk mixture (not the hot chocolate) to minimize evaporation. Keep milk at 55g.
  • The white chocolate does a lot of the heavy lifting here — use good quality baking white chocolate with real cocoa butter for the best flavor.
  • 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.