Rotiboy’s Original Coffee Bun Recipe

I remembered when I was a kid and Rotiboy came to Indonesia. The Malaysian bakery chain started popping up branches all over Jakarta and of course knock off bakeries followed soon after. Rotiboy only sold one kind of bun, at least, they used to. I think these days there’s another one or two different kind of buns available in the bakery. The OG Rotiboy, and the only Rotiboy bun in my head, is a coffee flavoured bun with a butter filling. Yes, a literal cubed of butter is stuffed inside the bun. If you’re anything like me, that sounds pretty delicious, but I can understand how some people may not find a bun stuffed with pure butter too appealing. The dough itself is already enriched with butter after all. What makes this bun special is the coffee cooking topping that surrounds the soft brioche bun. The bun itself is actually a plain yeasted brioche dough. It’s the cookie dough-like topping on the outside that gives the coffee flavour. It’s soft and chewy on the inside and the cookie dough gives it a crunchy crust.


As to why it’s called a Mexican Bun? I have no idea. It doesn’t seem to have anything to do with Mexican. To the best of my knowledge, it was a pure Malaysian creation. My best guess is that these buns are reminiscent of the Mexican Conchas, a sweet bun topped with a cookie crust shaped similar to a seashell. Like Rotiboy buns, Conchas consist of an unflavoured basic bread bun that is then topped with a cookie dough that can be coloured or is typically flavoured with chocolate or vanilla. The cookie topping is then scored in different ways to decorate the bun. So these buns are very similar to Conchas, we just don’t score the cookie topping, preferring a smoother top.



Of course I had to put my own spin on these Rotiboy coffee buns. After a consultation from my first batch with Rollo, we decided that a crème patisserie filling instead of butter would provide more nuance. Hence, the next day, I immediately went and made a crème patisserie which I would use the day after. I have to say, as much as I love the butter filling, the crème patisserie made the bun better! As the custard cream melts as the buns bake, it made the insides of the buns very soft at the same time, flavouring the bun with its rich custardy sweetness. I kept the cookie layer unchanged. Whilst the insides are super soft and pillowy, the cookie melded with the bread creating a thin crispy layer. If you are baking these and have a bit more time on our hands, I highly recommend the custard filling. If not, a sube of butter still would be amazing, or keep the buns unfilled.



Another reason why the buns are soft and chewy is due to the Tangzhong roux I made prior to making the dough. I made a roux with 1:5 ratio flour to milk. The roux is then added to the final dough. I love using the Tangzhong method when baking bread because it makes it lighter and have a tender crumb. Trust me, you can totally feel the difference in texture. I made Rollo do a blind taste test and the buns with the Tangzhong roux came out victorious.


Now that I know how to make my favourite childhood bun, whenever I’m feeling nostalgic, I’ll whip these up. Not to mention, instead of buying one bun, I now can have 15! And they taste just as good!


Rotiboy (Mexican Buns) Recipe


(yields 15-17 buns)


  • 20g all-purpose flour
  • 100g whole milk

Bun dough

  • 400g all-purpose flour
  • 50g sugar (¼ cup)
  • 4g easy bake yeast (~ 1 ¼ tsp.)
  • 6g salt (~1 tsp.)
  • 200g milk (30-35 C)
  • 50g egg (roughly 1 egg)
  • All the Tangzhong (~100g)
  • 40g softened butter, cut into cubes (~ 2 ½ tbsp.)

Coffee cookie dough topping

  • 100g butter (~ 1/2 cup + 3 tbsp.)
  • 90g icing sugar (~ 1/2 cup  + 2 tbsp)
  • 70g egg (~1 1/2 medium egg)
  • 1 1/2 tbsp tsp coffee
  • 1/2 tbsp water
  • 100g flour (~3/4 cup)

Optional fillings

  • butter (unsalted/salted), cut into small cubes
  • crème patisserie (recipe below)



  1. Tangzhong: In a small saucepan over medium-low heat, use a whisk to stir flour into milk until smooth. Continue to whisk the mixture as it heats up. Slowly, it will thicken into the consistency of pudding or ganache. With a thermometer, it should reach 65C/150F. Take it off the heat immediately. If weighed, the tangzhong should roughly be 100g.
  2. Bun Dough: In a big mixing bowl, combine flour, sugar, salt and yeast. Stir to distribute everything evenly. In a smaller bowl, combine warm milk, egg and all the Tangzhong. Give liquids a good stir before mixing it into the bowl of dry ingredients.
  3. With a stand mixer (on speed 1) or on a lightly flour surface with your hands, knead the dough for around 5 minutes until smooth.
  4. Add butter one cube at a time and continue to knead until its incorporated before adding another cube. Continue until all cubes of butter is kneaded into the dough.
  5. Grease a clean bowl with butter before placing the dough inside. Let it bulk ferment at room temperature until doubled in size (about 1 hour).
  6. Punch out the dough and turn over to an oiled surface (I lightly oiled my countertop with butter grease so the dough doesn’t stick). With a weighing scale, weigh each bun at 45-55 grams (I got 16 buns).
  7. Optional Filling: Flatten each dough ball a bit, place a small cold cube of butter or a teaspoon of cold crème patisserie (recipe below) in the middle of the flattened dough. Fold all the edges of the dough into the middle, covering the butter/crème patisserie. Gently roll and shape the dough back into a ball. Repeat with other dough balls. Alternatively, the dough can remain unfilled. If so, skip this step.
  8. Proof the dough balls for the second time for 30 minutes.
  9. Pre heat the oven at 190C/375F.
  10. Coffee Topping: Meanwhile, make the cookie topping by creaming the butter and sugar with an electric mixer until light and fluffy. Add the eggs one by one, continue to beat the mixture and letting each egg be incorporated before adding the next. It’s okay if the mixture looks separated, the flour would help combine it later.
  11. Dissolve the coffee granules with water before adding it to the mixture. Once its incorporated, add the flour little by little until everything is mixed together and a soft dough is formed.
  12. Load the topping into a piping bag. Pipe the topping into each proofed bun. Be sure to cover the top of the bun entirely as you’d want the cookie to cover the whole bun as it bakes later on.
  13. Bake for 13-15 minutes until golden brown.
  14. Best served warm. Store in an airtight container in the fridge. To reheat, simple heat the oven to 180C/350F and place buns inside for 5 minutes.



Crème Patisserie


  • 195g milk
  • 28g unsalted butter (2 tbsp.)
  • 2 egg yolks
  • 50g granulated sugar (¼ cup)
  • 20g all-purpose flour (2 ½ tbsp..)
  • ¼ tsp. salt
  • 9g corn starch (1 tbsp.)
  • ½ tsp. vanilla paste


  1. While the dough is rising (or ideally the day before), make the crème patisserie filling.  Scald the milk and butter in a small sauce pan. You want bubbles to form around the edges but you don’t want to let it boil. Let cool slightly.
  2. Beat the egg yolk with a whisk in a heat proof bowl (pyrex)
  3. Add the flour, cornstarch, salt, and sugar and whisk together to form a thick homogenous paste.
  4. Add a little of the warm milk mixture the paste. Whisk to temper the egg and loosens up the paste. Add the remaining warm milk slowly, making sure you’re constantly whisking the egg mixture.
  5. With a fine meshed sieve, strain the egg mixture into the same saucepan used to heat the milk.  Straining it would help filter out any egg yolk that may have scrambled/cooked.
  6. Add the vanilla bean paste and heat the saucepan over medium low heat. Whisk constantly as the mixture slowly thickens. You’d want the mixture to be thick enough that whisking the custard would leave lines or indentations.
  7. Refrigerate the crème patisserie until cold and thick in a covered container for several hours (ideally overnight).
  8. Use the crème patisserie as the recipe above. Store in an airtight container in the fridge and it should last 3 days. Use remaining crème patisserie in a lot of other desserts (Portuguese egg tarts, cake, trifle to name a few. Crème patisserie is literally custard so the options are endless!)

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