Traditional Hokkien steamed egg cake (Fatt gou 发糕）

This is the Hokkien version which has a smile and is often seen as an offering for alter prayer. I've chosen this recipe based on this comparison. Even though it's not as Cantonese because it seems to use carbonated soda rather than pure beating, it might turn out less dense and require less steaming time. Original source is Monica's Kitchen but she only has a video and not transcribed. As Monica uses a 6" bamboo basket, I've transcribed the recipe and also adapted using Christine's recipe because she uses a 8" cake tin.

Ingredients
5 eggs
220g sugar (reserve 2 tsp for sprinkling)
250g cake flour
105g soda drink (e.g., 7UP or Fanta Orange)
Pinch of salt
1 tsp vanilla extract (optional)

Method
1. Prepare a 8" cake tin lined with baking paper.
2. Reserve 2 tsp of the sugar (for sprinkling). Add a bit of the sugar to the eggs and beat until incorporated. Continue to beat by adding sugar a bit at a time until all the sugar is used up.
3. Beat until pale and fluffy, ribbon stage.
4. Sift flour in several batches. Gently fold after each incorporation.
5. Slowly pour 7UP and fold in to incorporate. Batter will be quite thin.

6. Pour into prepared tin.
7. Sprinkle on sugar in a cross on the top to create the 'smile'.
8. Steam for 35-40 minutes until a skewer inserted comes out clean. Ensure that the cover is covered with a cloth to prevent the condensation from dripping onto the cake and spoiling the 'face'.

Recipe feedback:
- The cake needed another 10 minutes, 5 minutes to 'rest' after switching off the fire, and another 5 minutes because the skewer came out wet. So in total, 40 minutes steam with 5 minutes resting.
- Cake came out slightly dense and rather dry. I may not have reached full ribbon stage.
- As can be seen from the photos, the sugar cross didn't help it to rise at all.
- The slightly fizzy taste and the orangey Fanta taste was discernible.
- The cake may also have come out wet after 35 minutes precisely because of the unmelted sugar at the bottom.
- The cake wasn't sweet enough but where the sugar sank to the bottom, it was super sweet.
- In future, I'd omit the sugar cross and simply beat it in with the rest of the sugar. I'll also go for 40 minutes steaming and 5 minutes resting.
- I would also try reducing 75g from the flour to make it less dense and hopefully it wouldn't collapse
- I don't need the 'smile' that you find in Hokkien Fatt Gou but if I did, then I'll put in 1 tsp of baking soda to interact with the Fanta.