Edit History

Working on my chocolate genoise recipe and running into an issue with my sponge. For reference, I am using an 8x4" aluminum cake pan. My genoise makes 3-4 layers. I baked my batter at 350˚F for 40 minutes, mostly based on visual cues.

As you can see, the top slice had underdone batter that I was able to remove like a tumor. There's underdone batter in both the top slice and middle slice. However, the periphery of the middle slice, and the entire bottom slice, are overdone and dry. Does anyone have a fix for this? Specifically:

- How to bake the sponge so that the bottom isn't overdone and the center isn't underdone

- Bonus if you can help me get a flat top so that I can salvage a 4th slice from this recipe

My recipe:

• 7 eggs (430g)
• 215g granulated sugar
• 43g cocoa powder
• 8g kosher salt
• 86g cornstarch
• 172g pastry flour
• 43g ghee, warmed
• 8g vanilla paste

1. Add eggs, sugar, cocoa, and salt to mixer bowl and heat over double boiler while constantly whisking. Heat until hot to the touch, then remove from heat and whisk on high until doubled/tripled in volume. (I wasn't able to reach ribbon stage, probably because of the amount of cocoa, so I will be reducing the amount in the future.)
2. Sift together cornstarch and flour, then fold into batter until nearly combined.
3. Add ½-1 cup batter to the ghee along with vanilla paste. Mix vigorously until combined and smooth. Gently fold this portion back into the whole cake batter.
4. Bake in preheated oven at 350˚ for 40 minutes.

[UPDATE]

Thank you for your suggestions! They were incredibly helpful, and because of your input, I was able to make a huge breakthrough.

Please ignore the tunneling...I was in a bit of a time crunch and should have been more thorough. My two changes were:

• I mixed my cocoa powder with just enough hot water to make it into a homogenous paste. Once my eggs and sugar were at ribbon stage, I took a portion and folded in my chocolate paste, then poured that mixture back into the batter while it was mixing at low speed. I let the mixer run until the mixture was homogenous, then folded in my dry ingredients and ghee/vanilla like normal.
• Reduced the oven temperature to 325˚F and baked the cake for 50 minutes.

Because of these changes, I got a sponge that was as moist on the top slice as it was on the bottom, however there was no underdone batter. The cake rose nicely and I was able to get 5 layers from i, which exceeded my expectations! Updated recipe below: 

My UPDATED recipe:

• 7 eggs (430g)
• 215g granulated sugar
• 43g cocoa powder
• 75g boiling water
• 8g kosher salt
• 86g cornstarch
• 172g pastry flour
• 43g ghee, warmed
• 8g vanilla paste

1. Add eggs, sugar, and salt to mixer bowl and heat over double boiler while constantly whisking. Heat until hot to the touch, then remove from heat and whisk on high until the mixture reaches ribbon stage, 5-6 minutes.
2. While the batter is mixing on high speed, dissolve the cocoa powder into boiling water and mix to a smooth paste.
3. Turn the mixer speed down to medium-low. Take ½-1 cup of the batter and fold in the chocolate paste. Gradually add the chocolate batter to the main batter and allow mixture to mix until homogenous.
4. Sift together cornstarch and flour, then fold into batter until nearly combined.
5. Add ½-1 cup batter to the ghee along with vanilla paste. Mix vigorously until combined and smooth. Gently fold this portion back into the whole cake batter.
6. Bake in preheated oven at 325˚ for 50 minutes.