Unraveling the mysteries of the steamed sponge cake

First off, OMG  it's been a year since I last blogged! Few reasons for that: 1) was still busy studying and 2) I picked up a new hobby. If you can't tell by now... it's baking and cake decorating! (SkillsFuture FTW hoho)

One year, a postgraduate degree, and Wilton courses 1 and 2 later, I'm back with something else for this blog. Was too lazy to blog about my past bakes, but you can check them out on Instagram @mao_vellous_cakes.

So the story of this post begins with SIL delving into nutella blossoms (steamed cake with nutella filling). Between us, we made several attempts, but all were hard and gummy after cooling thoroughly. We kinda gave up. Recently, our interest in the steamed cakes were revived with the enjoyment of these cakes procured from BreadTalk and Four Leaves. How on earth did they stay so soft and fluffy even after cooling? I found a recipe online from Ellena Guan that was touted to be similar to the baked goodies from Four Leaves, so I have been dying to try it since 2 weeks ago. But! I looked at the recipe and noticed there was no oil. I compared it to my tried and tested sponge recipe from CIL, which has oil in it. I decided there was no way to know unless I tested both. It went something like this:

What! They all turned out different!

Although they look the same, I can assure you the textures are quite different

For the first test, I used Ellena's recipe, which has no oil. However, I changed the method of mixing the ingredients, which is to separate the whites and yolks, then incorporate slowly (not the usual 2-step chiffon method, I'll get to that later). I wanted to see if steaming had the same effect as baking with a water bath. These were done in one batch with brown sugar. The result*:
- steamed version domed nicely, surface was smooth as a baby's bottom, but was just way more dense
- baked version had minimal doming, but cracked on the surface and was tacky to touch

For the second test, I used my tried and tested recipe from CIL that I have successfully made beautiful soft sponge cakes and chiffon rolls with. I had intended to steam the entire batch together, but by accident, divided it into high and low heat batches because my steamer wasn't big enough. These were done with maple syrup as the liquid (yum!) The result*:
- the ones steamed on high heat rose and domed less, and was slightly denser
- the ones steamed on low heat rose and domed more, and remained very soft

*results compared after cakes were thoroughly cooled. These cakes tend to be deceptively soft when warm, but turn into bouncy balls once cool.

Here's the lowdown on each:

No oil, steamed

This was Ellena's recipe using brown sugar, but I left out the ovalette and coffee powder, and changed the method (scroll down for recipe). These were steamed for 5 min on high, then 5 min on low heat (you can see the line in the cake where the temperature changed). It rose well, was smooth on top, but was gummy and chewy. It was a coarse crumb and difficult to slice. This was nowhere near Four Leaves' style, but felt more like Malay cake (马来糕) or huat kueh. The testers (GY, E1, E1, and GM) did not particularly like this cake.

I don't know why, but this just did not work for me. It was the same experience with past attempts. I figured it was down to the lack of oil or the technique of steaming. Or maybe this steamed cake just hates me. Whatever it is, I'm done with any recipe that does not have oil in it. Next.

No oil, baked

The other half of Ellena's recipe went into the oven, with a tray of hot water underneath. These baked at 160 deg convection for 12 min. The texture was much fluffier than the steamed batch but also had a coarse crumb. This performed like a regular sponge cake in the oven without the water bath. The only problem was that the surface remained tacky even after cooling. It was a nice enough cake, but it had neither the nice rounded dome nor the texture I was looking for. E1 and E2 liked the taste of the brown cake.

With oil, steamed on high heat

 This batch was done with the tried and tested sponge recipe, courtesy of CIL who says she got it from a Taiwanese cookbook. Again, I steamed it on high heat for 5 min, then lowered the temperature for the next 5 min - you can see once again where the temperature change affected the rise of the cake. Many steamed cake recipes out there are up in arms on whether to steam on high or low heat, with times ranging from 7 - 15 min. I decided to turn down the heat halfway since SIL, who also tried this recipe, said 12 min was way too long. This cake was smooth on the surface but did not rise much. What baffles me is why this cake did not rise and dome like the previous recipe when both were using high heat. Oil doesn't like the high heat? I dunno. Overall, the cake had a tight crumb with a softer texture than the previous batch, but I felt it was slightly chewy, like it had more 'bite' to it. GY and E2 picked this as their favourite out of all four. If I were to do this again, I might try high heat for 8 min straight.

With oil, steamed on low heat

 This was the accidental batch left out of the too-small steamer. I steamed these on low heat for 8 min. These cooked faster because there were only 2 cakes for this steaming batch. It had the most rise and dome, with a smooth surface. The texture was soft and fluffy like a chiffon. But interestingly, both GY and GM said it was sweeter than #3, which is weird because they were made from the same batter. This was E1's, GM's and my favourite pick out of all the cakes.

 Verdict: Ellena's recipe did not work for me as a steamed cake, but the baked version was ok. The recipe with the oil was unanimously the most popular, which is unsurprising since fat is what gives cake a soft texture. Between the high- and low-heat versions, we were more or less evenly split between the two, so I suppose it comes down to personal preference.

And with that, I give you the recipe for this no-longer-elusive steamed sponge cake:


Maple Steamed Cake

Makes about 8 cupcakes

Ingredients:

2 eggs
40g caster sugar
1g cream of tartar

20g caster sugar
20g maple syrup
15g vegetable oil (I use canola)
50g cake flour
1.5g baking powder, double acting
1/2 tsp vanilla extract

Method:

1. Prepare the steamer, letting water boil on high heat. Also prepare your cupcake liners in ramekins/trays/whatever cooks your cake. I used disposable aluminium souffle cups.
2. Separate egg whites and yolks. Place egg whites, 40g sugar and cream of tartar in mixing bowl. With electric mixer or balloon whisk of stand mixer, beat on high until stiff peaks form.
3. Add yolks one by one, beating thoroughly between each one until fully incorporated.
4. Add maple syrup and vanilla extract and beat thoroughly.
5. Sieve in flour, baking powder, and 20g sugar. Omit the sugar if you prefer it less sweet. (Keep the sugar if you replace the maple syrup with other liquids such as milk or juice) Using a wire whisk or spatula, fold gently until fully mixed (I prefer the whisk).
6. Lastly, gently fold in the oil.
7. Divide the batter between casings, or if using smaller/bigger casings, fill until 3/4 full. Batter is quite thick like soft whipped cream.
8. If you prefer a firmer texture, steam on high heat for about 8-10 min, depending on the size of your steamer. For a chiffon-like texture, steam on low heat for about 8-10 min. Always check with a toothpick/cake tester before steaming for longer times. 

Note: The timings are similar for both high and low heat because it depends on how big the steamer is and how many cakes there are inside. For my tests, I cooked 6 cakes on the high-heat version and 2 cakes on the low-heat version, hence the adjustments. Where in doubt, it's always better to undercook than to overcook!