Mexico Buns

This recipe is from Happy Home Baking which was well written with every single detail.  Please do visit here if you wish to bake these buns.

Below is the recipe copied from Happy Home Baking with her consent which I'm keeping here for future reference. There are some little adjustments to the measurements. 

Ingredients
[makes 10 buns]
tang zhong (water-roux):
25 gm bread flour
125 ml water
bread dough:
210 gm bread flour
60 gm cake flour
20 gm milk powder
40 gm caster sugar
1/2 tsp salt
6 gm instant yeast [I used 2 tsp]
1 small egg, lightly beaten
85 gm water
84 gm tang zhong (water-roux)* - I used all of the above tangzhong
20 gm unsalted butter
topping:
50 gm unsalted butter
50 gm caster sugar
50 gm egg, lightly beaten [I used 1 large egg]
50 gm cake flour
1 1/2 tsp instant coffee powder
1/2 tsp vanilla extract
1/2 tsp warm water
Method to make topping:

* Dissolve instant coffee powder with the warm water, mix in vanilla extract. Set aside.

* Beat the butter with caster sugar, until light and fluffy. Add the beaten egg one teaspoon at a time, beat well after each addition (add in egg gradually to prevent the mixture from curdling).

* Add in the coffee mixture gradually, beat well after each addition. Sieve over the cake flour. Mix with a spatula until just combined. Transfer topping into piping bag fixed with pipping nozzle (round tip).

* Let the topping chill in the fridge until needed. Remove from fridge about 5~10mins earlier before use to allow the topping to soften a little. 

Method to make tang zhong:

1. Place 25 gm bread flour in a saucepan. Add 125 ml water, mix till smooth, making sure there are no lumps of flour.
2. Cook over medium to low heat, stirring constantly with a hand whisk to prevent it from burning. Within 1 to 2 mins, the mixture will start to thicken, stop when you see traces in the mixture for every stir you make with the hand whisk. The 65 degrees C tang zhong is ready. 
3. Immediately transfer the hot tang zhong into a bowl and cover it with a cling wrap, making sure the cling wrap sticks onto the surface of the mixture. This is to prevent a film from forming on the surface. Leave to cool completely before using it.

Method to knead dough by bread machine:

1. Place water, egg, tang zhong (use 84 gm), sugar, salt, bread flour, cake flour, milk powder in the pan of the bread machine (according to the sequence as stated in the instruction manual of your bread machine).
2. Make an indentation on the flour and add in the instant yeast. Select the Dough function of the bread machine and press start. Leave the lid of the machine open (this is to prevent over heating). After about 10 mins of kneading, add in the 22 gm of butter. Let the machine continue to knead the dough. After the kneading cycle has stopped (20 mins), Stop and Restart the machine. Continue to let the machine knead for another 20 mins.
3. Remove dough from the bread pan. (Note: refer this post for instructions on how to knead dough by hand.)
4. Grease hands with some vegetable oil (this helps to prevent the dough from sticking to your hands). Remove dough from bread machine. 
5. Shape into a smooth round. Place dough in a lightly greased (use vegetable oil or butter) mixing bowl, cover with cling wrap or a damp cloth and let proof in room temperature (around 28 to 30 degrees C) for about one hour, or until double in bulk. 
6. Remove the dough from the bowl and give a few light kneading to press out the gas in the dough. Divide the dough into 10 equal portions (about 55 gm each).
7. Roll each dough into smooth rounds and place on a greased (or lined with parchment paper) baking tray.
8. Space doughs two inches apart to allow them to expand. Cover with damp cloth or cling wrap and leave doughs to proof for the second time for about 30~40 mins, or until double in size. 
9. Pipe topping onto each dough. Make sure to cover the entire surface with the topping. 
10. Bake in pre-heated oven at 180 degrees C for 15 mins or until golden brown. Remove from oven and transfer to wire track to let cool. Once cool, store immediately in an airtight container. Best served warm (re-heat in oven if necessary before serving).