Recipe: Pineapple Topping (for Chinese egg custard buns)

Hey, I've been looking for a recipe for the same exact tasty little pastries. anyway, I ended up finding this thread and it has a recipe on it but the topping seems to have stumped you guys as well. However, through endless internet searching I believe I have found the recipe for the topping (which I found out is called "Pineapple topping", it has no pineapple in it, it just looks like pineapple skin, I guess?)

Anyway this is the recipe for the topping, haven't tried it yet, but let me know if it works...

PINEAPPLE TOPPING

1/3 cup sugar
1/4 cup butter
1 egg yolk
1/2 tsp baking soda
2 tbsp milk
1 cup flour
2 tsp baking powder

Beat butter and sugar until creamy and fluffy. Add egg yolk, baking soda, and milk. Mix well.

Sift flour and baking powder into the butter mixture. Mix by hand until smooth and not sticky, being careful not to form gluten. Chill topping, wrapped in plastic, in refrigerator for 1 hour or more.

Right before baking your bao (after the dough has expanded), roll out your refrigerated pineapple topping to a 1/2 cm thickness, manipulating the "dough" as little as possible. If too dry, add a small amount of oil. Use a cookie cutter or a glass to cut out circles (12 total) that are slightly less wide than your buns.

Brush the buns with a small amount of water, and place your pineapple rounds on top. Lightly score the toppings with a criss-cross pattern, and brush buns with egg wash.

Try it and tell me if it works!!