HK/Macau paper-wrapped cupcakes

I have wanted to try this recipe for some time but never found the time to. It looks like a simpler and more delicious version of the steamed 鸡蛋糕. Here are the recipe comparisons:

Chiffon method
1. Nasilemaklover
- makes 7 in speciality mould
- Uses 4 eggs, separated
- Uses self-raising flour
- Uses beater for chiffon method
- Uses oil

2. Christine's recipes
- Original recipe with speciality tin: makes 6
- Pandan paper wrapped with speciality tin: makes 8
- Uses 5 eggs and cake flour
- Uses beater for chiffon method
- Regular flavour uses melted butter but pandan flavour uses oil

Creaming method
1. Rasa Malaysia
- makes 16 mini ones
- Uses 4 large eggs and normal flour
- Uses beater for creaming method
- Uses oil

2. Ancoo - Tried below
- Makes 15 mini cakes
- Uses 4 egg yolks and 3 egg whites (what am I going to do with an extra white?)
- Uses cake flour and corn starch
- Uses beater for creaming method
- Uses melted butter

Ingredients - makes 12
4 egg yolks
3 egg whites
1 tsp vanilla
70g sugar
70g cake flour
10g (1.5 tbsp) corn starch

Muffin cases in the egg tart tins

½ tsp baking powder
75g melted butter

Method
1. In a bowl, cream the 4 egg yolks and 3 whites with the sugar at high speed for 5 minutes until pale yellow and thick. Lower to low speed and beat for 1 more minute.
2. Sift the flours and baking powder.
3. Add the flours batter in two batches, and fold in.
4. Take a bit of the batter and add in the melted butter. Combine well. Return this to the main batter and fold in.
5. Pour into prepared tins. Traditionally, the flower shaped tins with parchment paper inserted are used. I only had muffin cases which I inserted into egg tart tins.
6. Pour ⅔ full. It will be quite liquidy. Tap gently on the counter to remove the air.
7. Bake at 180 deg C for 15 minutes until a toothpick inserted comes out clean. I turned it at the 15th minute because the browning was uneven.
8. Remove the muffin cases to a wire rack to cool. Serve warm.