Hojicha and sweet black bean sponge roll

And how to make it all your own

Sponge rolls are such a fun, blank canvas to play around with in the kitchen. Kept at their simplest, all you need is a layer of fluffy sponge, some whipped cream and fresh berries. How about a custard filling? Or a hazelnut-chocolate filling? Ricotta? Mascarpone and pistachios? The Tuscan coast favourite, known as tronco (‘log’) is filled with a chocolate filling and brushed with pink Alchermes.

You could really do anything with them and any combination of flavours — even savoury. I remember my mother making a pillowy smoked salmon roulade like this when I was a child in the 80s. And aside from the daunting aspect of rolling the thing together, it really is a very simple recipe and only needs 10-12 minutes of baking.

I started with kuromame, black soy beans simmered with soy sauce and sugar, a special Japanese new year food that I adore. I made them from scratch using this recipe (Nami’s blog is my go-to for traditional Japanese recipes) but you can also purchase them ready made in packets — in Italy you can buy them online from Milan-based Todoku. They have a thick skin so maintain quite a good bite to them and have a texture similar to cooked chestnuts, which would be quite a good substitute.

Since I had obviously made way too many of these over the new year (because I love them so) I was looking for a new way to use them and came across a hojicha sponge roll filled with sweet whipped cream and carefully placed kuromame from a cookbook by Junko Fukuda which sounded just the thing. I absolutely love Japanese flavours in European desserts like this, so it appealed right away. Hojicha is green tea that has been roasted rather than just steamed — supposedly a happy accident created by a Kyoto tea seller a century ago — which is what gives it its deep brown colour and less bitter, more earthy, smoky flavour. I love it, actually prefer it to regular green tea, along with genmaicha which has a similar toastiness.

I used my own trusty sponge roll recipe, which you can find here and in Acquacotta, for a classic tronco. It’s easy to make this gluten-free too, if you use just all cornstarch. I only very slightly sweetened the cream with a bit of powdered sugar — there’s quite a bit here but save the extra in case you too hurriedly roll the sponge and find cracks as I did here. Nothing a lathering of cream over the top couldn’t cover!

Now, feel free to make this yours. Instead of hojicha, try powdered matcha, or grind Early Grey tea leaves. Try even a spoonful of ground coffee instead. If you don’t have kuromame, you can try sweet adzuki beans, or roasted or boiled chestnuts (or candied, aka marron glaces, they will be much sweeter so you can use less of them and cut them into tiny pieces), even candied fruit, or fresh seasonal fruit. I am thinking something like peeled mandarin segments or homemade candied orange peel would be really lovely in this. The creamy filling could be any of the ideas I already mentioned above (imagine ricotta!).

And don’t forget, you can brush the sponge with a further layer of flavours in the form of a liquid or syrup, which helps keep the cake moist and supple for rolling. It could be a simple syrup (half sugar, half water) that you can flavour with lemon zest, vanilla or add a splash of your favourite liqueur to. It could be tea, as I used here, coffee, or fresh orange juice. You could infuse the syrup with herbs or spices (rosemary! Bay leaves! Cinnamon!) or anything your heart desires really. And we didn’t even get into the possibilities with jam. As I said, a blank canvas.

Hojicha and kuromame sponge roll

I made this as a birthday cake for my mother, who is miles away so won’t get to eat it but I think she would really love this as it’s not very sweet. If you prefer a tiny bit more sweetness, you can top this with powdered sugar or add a little more in the cream to taste.

For the hojicha powder, if you don’t have the actual powder (like this one), you can take the regular leaves and grind them in a coffee grinder or with a mortar and pestle (I did it this way). Sift them and use just the fine powder — and with the rest, brew yourself a nice cup of hojicha to sip on while you make this! Just save a little bit for brushing over the cake later.

Serves 6-8

3 eggs
100 grams (1/2 cup) fine sugar, plus an extra teaspoon or two
50 grams (1/3 cup plus 1 tablespoon) cornstarch
50 grams (1/4 cup) flour
1 tablespoon of hojicha powder (see note above)
250 ml (1 cup) cream for whipping
2 teaspoons powdered sugar (or to taste)
3 tablespoons of kuromame

Preheat the oven to 160ºC and line a 23 x 33 cm baking tray with baking paper (alternatively, use a flat baking sheet such as a cookie sheet and try to shape the batter to this size, roughly, which is a tiny bit bigger than a sheet of A4 paper).

Separate the eggs in two clean metal or glass mixing bowls, yolks in one and whites in the other. Whisk the whites until stiff peaks form, then whisk the egg yolks and the sugar with an electric mixer or electric egg beaters for up to 10 minutes, or until the yolks become very pale, fluffy and creamy (if you happen to this in the opposite order, make sure to clean the beaters very well before whisking the whites — fat from the yolks stops them from forming stiff peaks). To the creamy egg yolks, gently fold in half of the whites and then sift in the flours and hojicha powder, folding until no raw flour can be seen, then fold in the rest of the whites gently until combined.

Pour the batter into the lined baking tray – the batter should be about 1 cm high. Bake in the oven for about 10–12 minutes, or until the top is very pale golden and springy in the middle. Careful not to overbake this. Remove the sponge from the oven and let it cool ever so slightly so you can handle it easily – you still want to work with it while it’s warm.

I used to do this step with plastic wrap but I no longer use plastic. A sheet of baking paper or greaseproof paper, or even a clean linen tea towel could be used instead. Spread out a clean sheet of baking paper and scatter it evenly with the extra spoonful of sugar (this helps to stop the sponge from sticking). Gently turn the sponge upside down onto the prepared baking paper. Remove the baking paper from the cake. With a bread knife, trim the edges slightly – this will stop the sides from cracking as they roll. Then, with a pastry brush, stain this side of the sponge evenly with some of the hojicha tea that you brewed while you were making the batter. You can do a couple of “coats”.

Whip the cream in a large bowl with the powdered sugar, then generously spread it over the top of the sponge so that it is about 1.5 cm thick, smoothing out evenly and leaving a 1 cm border around the edges. Scatter with kuromame (save some for the top for decoration if you like).

The rolling part rather reminds me of rolling sushi The tricky part is really in starting the roll – the rest is all about the right amount of pressure (not too tight, but not too loose). Picking up the short end of the sponge with the help of the baking paper underneath, carefully roll the entire thing up firmly and then secure by rolling the paper completely around it. Keep it like this on a plate in the fridge to set for 1 hour.

If you like, you can add more cream over the top and decorate with more beans, or leave as is, simply dusted with powdered sugar. Serve in thick slices.