For the filling, I heat the yogurt, cream, and agar-agar gently until the agar activates, then let it cool slightly before folding in raspberries. The mixture thickens beautifully as it cools, and spreading it over the unrolled sponge feels incredibly satisfying. I roll everything back up carefully, wrap it tightly, and chill it until set. That waiting time is hard, but it’s absolutely worth it.
Pro Tips for Best Results
I tested this recipe several times, and one thing I learned is that the sponge texture depends heavily on egg handling. Make sure your egg whites are whipped to soft, not stiff, peaks. Stiff peaks make folding harder and can deflate the batter unevenly, leading to a tougher cake.
Temperature control is another lesson I learned the hard way. If the sponge cools too much before rolling, it’s far more likely to crack. Rolling it while still warm, even if it feels a bit scary, gives you a much smoother final result. I’ve tried letting it cool fully first, and trust me, that approach doesn’t work nearly as well.
For the mousse, patience is key. Let the yogurt mixture cool just enough so it thickens slightly before spreading. If it’s too warm, it will seep into the sponge and make it soggy. I’ve rushed this step before, and while it still tasted good, the texture wasn’t nearly as clean.
Finally, don’t overload the roll with filling. It’s tempting because the mousse is delicious, but too much will squeeze out the sides. I’ve learned that a thin, even layer gives the best spiral and the most professional-looking slices.
Common Mistakes to Avoid
One mistake I made early on was overmixing the batter after adding the flour. It’s easy to think you need to smooth everything perfectly, but overworking it develops gluten and ruins the delicate texture. Now I stop mixing as soon as everything is combined, even if it looks slightly uneven.
Another common issue is under-whipping or over-whipping the egg whites. Under-whipped whites won’t provide enough structure, while over-whipped ones make folding nearly impossible. I watch closely and stop as soon as the whites hold soft peaks that gently droop at the tips.
I also learned not to skip lining and greasing the pan properly. One time, I rushed and didn’t grease the parchment enough, and the sponge stuck just enough to tear when I flipped it. That extra minute of prep saves a lot of frustration.(See the next page below to continue…)