I've been baking this recipe for over a year now, flavour and texture are wonderful, the guests love it but half of the time I get these air pockets on the bottom of the cake.

The air pockets appear at the center of the bottom and also at the sides. Sometimes they're barely there, sometimes they're big enough that I'm unsure if i'll serve it to guests (for exemple when they're 3cm height).

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Recipe is as follows:

  • 150g cashew nuts (roasted, unsalted) chopped in a food processor
  • 30g white flour
  • 125g sugar
  • pinch of salt
  • 4 egg whites, lightly beaten with a fork
  • 150g butter, heated untill brown
  • 1/2 teaspoon vanilla extract

Everything at room temperature.

Preparation is staightfoward: mix dry ingredients, add egg whites, add butter and vanilla. Cooks at 160~180C for 45~50m untill golden brown. Lower temperatures do not make the bubbles disappear.

What causes these air pockets? Has anyone faced a similar issue before?

  • 1
    Pretty pourable! No need to spread. I also bang the cake pan before going to the oven.
    – maya
    Commented Nov 26, 2020 at 15:08
  • 1
    @GdD The thing is that the holes aren't inside the cake. When i cut a slice, it's perfectly smooth in texture. The bubble is forming only on the bottom, on the outside of the cake. Despite that, I already tried to run the knife and also to bang the cake pan - to no effect, sadly...
    – maya
    Commented Nov 26, 2020 at 15:29
  • 1
    @maya, dupe is short for duplicate, apologies for confusing you. I am wondering if the same thing happens in a different pan. It could be part of the bottom of the pan has some sort of imperfection which transfers heat differently from the rest. The cake looks very nice anyway, makes me want a slice!
    – GdD
    Commented Nov 27, 2020 at 15:36
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    @GdD Oh I get it now! Well, I bake that cake often, sometimes twice a week. I have 3 pans, same size and material, but purchased along the years... I had my suspicions about a heat spot, but the many pans and 2 ovens do make that unlikely. The weirdest part is that half of the time the cake will turn out perfectly smooth on the bottom, out of the blue
    – maya
    Commented Nov 27, 2020 at 15:51
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    @Joe The pictures show the air pocket that forms at the center and also the small pockets at the edges. After 10m at room temp if comes out of the pan with no struggle. The bubbles are underneath the cake, so only when unmolded can I see if I got them or not. I'm planning to bake one at a pyrex dish and watch it cooking so I can hopefully see when and how they form.
    – maya
    Commented Nov 28, 2020 at 18:49

1 Answer 1


That happened to me as well. Luckily it doesn't change the taste, but it is annoying! It comes from air pockets which formed because you whisked/mixed your cake batter too intensely, and/or for too long, which creates air bubbles. So first, it is best to mix your ingredients delicately, try to avoid incorporating too much air (easier said than done), and stop whisking once your batter reached the desired homogeneous consistency (overwhisking is a common mistake). Then, when you pour your cake batter in the pan, it's better to avoid pouring it all at once in the center, it will also create air bubbles. It's better to pour it delicately from one corner and let it spread by itself in the dish. Finally, before putting in the oven, tap (delicately) the bottom of your pan on the counter to free the remaining air bubbles and let them reach the surface before cooking. I hope that will help, let me know!

  • At first I also thought I was overmixing. I reduced the mixing steps to 20 or 30s, just untill the ingredients are combined. But bubbles kept coming from time to time. I always poured the batter at the center, I can't see how that would create bubble, but I always tap it before baking. I will try pouring from a corner! From the date of my entry I've experimented with this recipe, baked 42 of them taking notes. No clear answers still. But I discovered this is a kind of "financier", a french cake.
    – maya
    Commented Jan 5, 2021 at 21:51
  • Interesting, and very mysterious! Does it happen only with this specific recipe or with others as well? Have you tried baking it in smaller quantities? Normally financier is baked in a small pan, so maybe the batter doesn't react the same way in a bigger one?
    – Sarah BDnO
    Commented Jan 6, 2021 at 9:59
  • The bubbles appear even in small cupcake format. But I like to make mine as a whole cake, following the recipe. The bubble persists with all nuts: pistachio, cashew nuts, almonds... My guess is that water from egg whites is the main leavener agent. Steam must be forming in big quantities at the start of heating, creating those big bubbles.
    – maya
    Commented Jan 10, 2021 at 23:05

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