Cantonese Steamed Sponge Cake (馬拉糕)

Cantonese Steamed Sponge Cake (馬拉糕, pronounced as Ma-La-Gau) is a dim-sum dessert. It's steamed, not baked, hence more moist than the usual sponge cakes. This was made at the beginning of 2019, when Papa's mom was still able to eat a cake like this. We largely followed what's in one of those out-of-print Wei-Chuan recipe books (味全食譜), with minor adjustments here and there.

1. Line a 8”x8” glass baking pan with plastic wrap;
2. Place 5 eggs and 1 cup brown sugar into a stand mixer, and beat to creamy color; 
3. Melt 1/2 cup of butter or shortening in Microwave (30 seconds), stir with chopsticks, heat in Microwave for 15 seconds again. Add 1/4 tsp of vanilla extract, and 3/4 cup of evaporated milk (or, 1/2 cup half and half). Pour both the melted butter and the evaporated (or half and half) into the stand mixer, beat for 1 more minute; 
4. [Dry Ingredients] Mix thoroughly 2 Tbsp baking powder, 0.5 cup corn starch, and 1.5 cups flour, Sift the dry ingredients-mix into the stand mixer; 
5. Use a spatula to fold and mix the Dry Ingredients with the beaten liquid thoroughly. Pour the mixture into the 8”x8” glass pan.
6. Place the glass pan (uncovered) into a steaming pot, turn on high heat till full steam, then reduce to medium heat for 30 mins. Note- The cake needs enough room to rise up (4-5" in height). The top steaming basket along with a dome-lid should be high enough. Also we need wipe the inside of the dome-lid clean, to avoid vapor drops coming onto cake surface (instead of flowing smoothly to the side of the pot). The result from our kitchen is at the top of this post.