Mexican Coffee Buns / Roti Buns 墨西哥咖啡面包

I'll start with telling you that Mexican Coffee Buns is not original from Mexico but from Singapore or may be Malaysia. There are Papa Roti, Mama Roti and Roti Boy stores selling this  Mexican Coffee Buns or Roti Buns. It is a bun with butter filling, and with a layer of cookie crust on top. Yes, it is famous because of its coffee fragrance crust and the soft texture bread. And I have not taste any Mexican Coffee Buns while I was in Singapore just because I can't take coffee, food or drink with caffeine in it will increased my heart beat and causing nausea. But then I realized the coffee bun which Papa Roti/ Mama Roti/ Roti Boy selling is not literally with coffee but just that bit of coffee powder in the cookie crust on top. 

However, if you can't take caffeine like me, I suggest you reduce the coffee powder in the cookie crust, as that 1.5 tsp of Nescafe instant coffee powder still make me feel nausea after eating only one bun. While doing the search on Internet on coffee buns, I realized some people mentioned about the issue on collapsing of the cookie crust dome, I have not encounter this issue myself just suspect that it could be cause by under baked of the bun. My Mexican Coffee Buns, raised so beautifully with a brown, fat and crispy round dome! The most enjoyable part in baking this Mexican Coffee Buns is watching the topping melt and witness the expanding of its dome. With the used of water roux (Tangzhong) the bun texture is soft. If anything I want to change for future baking of this coffee buns that would be adding more butter filling, and only pipe the topping 1/3 of the bun instead of 3/4 of it.

Thanks Happy Home Baking for sharing her recipe. I refer to 陈郁芬65C 汤种面包，墨西哥面包 too. This coffee bun has to eat while it is hot, when it sit long in room temperature the cookies crust tends to turn a bit sticky, just pop it in the oven and reheat for 5 mins will make it good again. 

Yield: 10 buns

Ingredients Water Roux:
25g bread flour
125g water

Filling:

100g salted butter (can used 200g in future as 100g is way too little)
35g sugar
a pinch of salt (to taste, option)

Bread dough:

210g bread flour
56g cake flour 
84g water roux
40g sugar
1/2 tsp salt
30g milk powder
6g instant dry yeast
85ml water (gradually add)
1 large egg, lightly beaten
22g unsalted butter, cut into small pieces
extra flour, for dusting the dough and hands

Coffee Topping:

50g unsalted butter
50g icing sugar, sieved
1 large egg, lightly beaten
50g cake flour
1.5 tsp instant coffee powder
1/2 tsp hot water
1/2 tsp vanilla essence

Method:

Prepare water roux: in a small pot, cook the bread flour with water until it is thicken. Cover and set aside.

Prepare filling: Stir all ingredients for filling together, divided it into 10 portions, keep it in freezer until used.

Prepare coffee topping: 1. Dissolve the coffee powder in hot water, add vanilla essence. 2. In a bowl, Beat the butter and sugar until light and fluffy. Add egg mixture in batches, mix well after each addition. Sieve in the cake flour and add coffee mixture, mix until the mixture is smooth and combined. Keep the topping chill in fridge, remove 5 mins from fridge before used to soften the topping  a little.

Prepare bread:1. Mix all dry ingredients for bread in the KitchenAid mixing bowl. In a small bowl, whisk egg together with water.2. Gradually add water and egg mixture to the dry ingredients, use the KitchenAid speed 1 to mix all together for 1 min before change it to speed 4 for 10 mins.3. Add butter pieces, continue to let it knead until the dough is elastic and form window pane. The dough will pull away from the side of mixing bowl. 4. Transfer the dough to a lightly oiled bowl, cover and proof it to double its size. 5. Punch down the air, divide the dough into 10 portions. Roll the dough to form balls. Let it rest for 10 mins.6. Flatten the dough ball into a flat circle, place a tsp of butter filling in the middle and wrap it up. Seal the edges and seam side down. Place the dough ball two inch apart from each other on the lined baking tray. Let it proof until double its size. Repeat for the remaining dough and filling.

7. Preheat the oven to 180C.
8. Place the coffee topping in a piping bag, pipe the coffee topping on the bun dough, start from the center then go outwards, make the topping swirl as close as possible to the swirl before it.  
9. Bake at 180C for 15 mins or when the topping turn slightly brown and a soft crust is form on the bun.