In another bowl, I whisk the egg whites with a pinch of salt until they turn foamy, then gradually add the remaining sugar. I’ve tried whipping quickly and aggressively, but slower whisking gives me better control and a silkier texture. Once the whites hold soft, shiny peaks, I fold them into the yolk mixture in two additions, lifting from the bottom and turning the bowl gently.
I spread the batter evenly onto a parchment-lined baking sheet, taking time to smooth it out so there are no thin corners. I bake it just until the sponge is set and lightly springy, not golden. As soon as it comes out of the oven, I flip it onto a clean towel, peel away the parchment, and gently roll it up while it’s still warm, which helps prevent cracking later.
For the filling, I melt the white chocolate with the condensed milk over very gentle heat, stirring constantly. Once smooth, I remove it from the heat and stir in the softened butter, which adds richness and shine. After the sponge cools, I unroll it carefully, brush it with soaking syrup, spread the ganache evenly, and roll it back up with steady pressure. I finish by covering it with caramel sauce and chilling it until fully set.
Pro Tips for Best Results
I tested this sponge several times, and the biggest thing I learned is that flexibility matters more than color. A pale sponge rolls beautifully, while a golden one almost always cracks. Trust me, don’t wait for browning here.
Another important lesson I learned the hard way is to roll the sponge while it’s still warm. I once waited until it cooled, thinking it would be easier to handle, and it cracked instantly. Rolling it warm trains the cake to hold its shape.
When it comes to the white chocolate filling, gentle heat is non-negotiable. I overheated it once, and it turned grainy and dull instead of smooth. Low heat and patience make all the difference.
Finally, don’t skip the soaking syrup. I tested the cake without it, and while it tasted fine on day one, it dried out noticeably by the next day. The syrup keeps the sponge soft and pleasant even after chilling.
Common Mistakes to Avoid
The first mistake I made was overwhipping the egg whites. I thought stiff peaks would give more structure, but they made folding difficult and uneven. Soft, glossy peaks work best for this batter.
Another common mistake is spreading the batter unevenly on the baking sheet. Thin spots bake faster and crack more easily, so I always take an extra minute to level it properly.(See the next page below to continue…)