Vegan Okinawa Black Sugar Walnut Swiss Roll Cake (Japanese-style)

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Black sugar syrup (Kuromitsu) cream filling rolled in fluffy cake, this cake roll is delicious with a Japanese taste with crunchy toasted walnuts inside!

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

I’ve been thinking about making cake rolls for a long time. But after a few tries, I got a little bit frustrated and stopped trying for a while. Then I tried again with different flavor in mind, and it’s here!

日本沖繩黑糖蜜 Japanese Black Sugar Syrup

The push is actually Kuromitsu, a black sugar syrup (or molasses) from Okinawa, Japan. I’ve been loving black sugar syrup since I first tasted it. This time I got them from a Taiwanese sponsor (for the Chinese post only).

But this Swiss Roll Cake is really amazing and unique that I want to share it with more of my readers. (So, hi!)

日本沖繩黑糖蜜 Japanese Black Sugar Syrup

Kuromitsu, aka black sugar syrup, is one of the Asian food I find as irreplaceable as soy sauce. It’s rich, sweet-but-not-so-sweet flavor adds depth to baking foods and dishes. This cake will be totally different without it.

日本沖繩黑糖蜜 Japanese Black Sugar Syrup

Different from regular cane sugar, black sugar reserved the molasse so it contains a little more nutrients than its refined counterpart. It also adds a depth of flavor to the final product.

The taste of Okinawa black syrup is different from the molasses I bought on iHerb (aka the western version). It’s more subtle in terms of the molasses taste so it’s more similar to the Taiwanese version. Yet, it still has a deep flavor that the Taiwanese one doesn’t possess.

Okinawa black sugar syrup (Kuromitsu) works well with many foods. Normal combinations in Japan include sweet small desserts (Wagashi), mochi cakes (Kuzumochi), and pancakes. It’s also a great ingredient for cookies, cakes, and other baking goods.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

This cake roll is made with main 2 elements:

  • Soft, fluffy Black Sugar Syrup Cake made with whole wheat pastry flour and sweetened with dates
  • Creamy, delicious Black Sugar Syrup Crean Filling stuffed with toasted walnuts
純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

I add a special ingredient in the cake batter to make it more “Japanese.” It’s toasted soy flour or Kinako. As its name suggests, it’s a powder made from grinding toasted soy.

It has a very unique and nutty aroma that I adore so much. And I’m really familiar with toasted soy flour because I added it to my sweet pinto red bean soup when I was like 17 to 18. I still add it to my breakfast from time to time to add more flavor.

This cake roll involves a little bit more steps than usual, but when you taste it in the end, you’ll know it’s worth it. Well, at least I do. Let’s make it step by step.

自製椰棗泥 Date Paste

Preparation

First, we need to soak the pitted dates (with 120 ml water) and raw cashews (enough to cover all) separately for a least 3 hours. This step is really important to make the final cake soft and light.

For the cake

Let’s make the cake. In a bowl, mix the whole wheat pastry flour, corn starch, toasted soy flour (Kinako), baking powder, baking soda, and salt.

In a blender, add the pitted dates with the soaking water, additional water (320g), peanut butter, grapeseed oil. Blend until smooth.

Then pour the date mixture into the dry one, along with the apple cider vinegar. Mix until no lumps can be seen.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

Pour the batter on a lined baking sheet or jelly roll pan (10*15 inches, my baking sheet is 27*38 cm). Spread the batter evenly. Drop it against the counter a few times to remove the air bubbles.

Place it in the preheated oven at 175 C for about 20 minutes. You should know it’s done when you insert a toothpick in the middle and it comes out clean.

Remove the baking sheet/jelly pan from the oven and let it cool complete. In the meantime, let’s make the cream filling.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

For the filling

Drain out the water from the cashews and give them a gentle rinse.

Then add the soaked cashews, soy milk, coconut cream, and black sugar syrup in a blender. Blend until smooth. It might be runny at first, but it will thicken if you let it sit for a while.

Final assembly

Pour the filling mixture onto the cooled cake and spread it out evenly, leaving about an inch of space from the edges.

Place it into the freezer for 20-30 minutes. This step is to let the cream set up a little bit so it’s easier to roll.

Remove the baking sheet/jelly pan from the freezer. Sprinkle the toasted walnuts on top of the cream.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

Roll the cake up from the shorter side. Press a little bit every time you make a rolling move to tighten it up.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

You can enjoy the cake roll right away but I like to put the cake roll back in the freezer for another 10-20 minutes before slicing. This way the cake roll will be firmer and the cutting slices will be prettier.

Substitution & Notes

Can I use other flour instead of whole wheat pastry flour?

I personally haven’t tried it with other flour so I’m not 100% sure it will be the same with other flour. But I think all-purpose flour will be the best substitution candidate. And if you’ve tried it with other flour, let me know how it goes in the comment section below. I will add more notes for this post. 🙂

Can I replace grapeseed oil with other oil?

Yes, you can use other neutral-flavor vegetable oil (like avocado oil or sunflower seed oil) to replace grapeseed oil. Coconut oil should also work but just keep in mind that it will get a little bit harder after refrigerated.

How to store this swiss cake roll?

This cake roll should be able to stay in an air-tight container in the fridge for 3-5 days. If you want to keep it longer, you can slice the roll after it firms up and store the slices in a food container in the freezer for 2-3 weeks.

How to Serve this swiss cake roll?

You can enjoy it right away from the fridge or let it defrost if pulling it out from the freezer.

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

This cake is sweet but not very sweet, which is kind of the motto for my beloved desserts.

And different from common vegan cakes, it’s soft and firm, and the cream filling is rich but hot heavy. And I must say the toasted walnuts inside bring the whole cake roll to another level!

純素日式黑糖核桃蛋糕捲 Vegan Black Sugar Walnut Swiss Roll Cake

I hope you got a chance to give it a try and let me know how it goes. And if you’re hungry for more, check out:

Vegan Okinawa Black Sugar Walnut Swiss Roll Cake (Japanese-style)

Vegan Black Sugar Walnut Swiss Roll Cake (Japanese-style)

Black sugar syrup (Kuromitsu) cream filling rolled in fluffy cake, this cake roll is delicious with a Japanese taste with crunchy toasted walnuts inside!
Author: Nora Hsu
Prep Time3 hours 30 minutes
Freezing30 minutes
Total Time4 hours
Course: Dessert
Keyword: black sugar, dairy-free, vegan
Servings: 8 people

Ingredients

Black Syrup Kuromitsu Cake

  • 170 g dates, pitted
  • 440 g water, divided into 120 g and 320 g
  • 150 g wholewheat pastry flour
  • 2 Tbsp corn starch
  • 2 Tbsp toasted soy flour, Kinako
  • 1 1/2 tsp baking soda
  • 1 tsp baking powder
  • 1/4 tsp salt
  • 3 Tbsp peanut butter, or other nut butter
  • 1 Tbsp grapeseed oil, or neutral-flavor vegetable oil**
  • 55 g (4 Tbsp) Okinawa black sugar syrup, Kuromitsu
  • 2 Tbsp apple cider vinegar

Kuromitsu Cream Filling

  • 150 g (1 cup) raw cashews
  • 90 ml (3/8 cup) soy milk, or other plant milk
  • 6 Tbsp coconut cream, scooped from a canned refrigerated coconut milk
  • 60 g (4.5 Tbsp) Okinawa black sugar syrup, Kuromitsu***
  • 100 g (1/2 + 1/4 cup) toasted walnuts, roughly chopped

Instructions

Preparation

  • Soak the pitted dates with 120 g water and cashews with enough water to cover respectively for a least 3 hours.

For the cake

  • Preheat the oven to 175 C / 350 F. Line a baking sheet or jelly roll pan with parchment paper. (jelly roll pan is 10*15 inch, my baking sheet is 27*38 cm)
  • In a bowl, add the whole wheat pastry flour, corn starch, toasted soy flour (Kinako), baking powder, baking soda, and salt. Give them a mix.
  • In a blender, add the pitted dates with the soaking water, 320 g water, peanut butter, grapeseed oil. Blend until smooth.
  • Pour the date mixture into the dry ones and add the apple cider vinegar. Mix until no lumps can be seen.
  • Pour the batter on the lined baking sheet/jelly roll pan. Drop the pan against the counter a few times to remove the air bubbles.
  • Bake in the preheated oven at 175 C/350 F for 18-22 minutes. You should know it’s done when you insert a toothpick in the middle and it comes out clean.
  • Remove the pan from the oven and let it cool on a wire rack. In the meantime, let’s make the cream filling.

For the filling

  • Drain out the water from the cashews and give them a gentle rinse.
  • In a blender, add the soaked cashews, soy milk, coconut cream, and black sugar syrup. Blend until smooth****. It might be runny at first, but it will thicken if you let it sit for a while. (See the texture in the picture above)

Final assembly

  • Pour 2/3 of the filling mixture onto the cooled cake and spread it out evenly, leaving about 2 cm (an inch) space from the edges.
  • Place the pan into the freezer for 20-30 minutes to let the cream set up a little bit so it's easier to roll. Put the left filling in the fridge to use later.
  • Remove the pan from the freezer. Sprinkle the toasted walnuts on top of the cream filling.
  • Roll the cake up from the shorter side. Press a little bit every time you make a rolling motion.
  • Enjoy right away or put the cake roll back in the freezer for another 10-20 minutes. It will be firmer and the cutting slices will be prettier.
  • Take the cake out from the freezer and remove the parchment paper. Pour the left filling onto the cake roll. You can add a little bit of water to the filling if it's too thick to pour. Sprinkle with more toasted walnuts on top. Slice and EAT!

Notes

  • *Flour: I haven’t tested this recipe with other flour so I’m not sure other substitutes will work the same. But all-purpose flour will be a good choice.
  • **Oil: You can use other neutral-flavor vegetable oil for substitution, like avocado oil and sunflower oil.
  • ***Okinawa black sugar syrup: I cannot find the one I use on Amazon so I’m not sure if you could find it in your country. But this Okinawa black molasses is the most similar one I found on Amazon. I will post a homemade version in the near future.
  • ****Blending: On the first try, I couldn’t make the filling super smooth in my Vitamix 64oz blender container, so I changed to use my small 32oz container instead. It turned out to work much better at blending this mixture. I think it’s due to the volume of the mixture that it’s not enough to bring the large container to work smoothly. So if your blender has trouble blending, double the filling and it should work better. The other way is to use a smaller container (like 32oz container for Vitamix classic blender or 48oz for ascent series)or a smaller blender like a magic bullet.
  • Storage: Store in the fridge for 3-5 days or 2 weeks in the freezer.
Nora
Nora

我是 Nora 葉子,一個從 ED 恢復、熱愛烘焙料理的創作者,2018 年轉變成 Vegan,希望透過分享能讓大家更認識全植物食物的美好。

Hi, I'm Nora, a creative who loves baking, cooking, and sharing. After turning vegan in 2018, I hope to share my joy and wonderful plant-based recipes with the world.

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