Prepare the inti filling (can be prepared few days before and keep in the fridge):
If you use gula Jawa/gula Melaka, place the sugar in the saucepan and melt over low heat and then strain. Sometimes there are some impurities in the gula Jawa. You don't have to do this if you use coconut sugar
Mix all the ingredients for the filling. Place this over a medium-size skillet and stir-fry for over medium heat for about 2 minutes or so. The sugar will start to dissolve (if you use coconut sugar) and the mixture will be "wetter". Stir fry again until the mixture is dry. Sprinkle in 1 Tbsp of all-purpose flour and stir to mix. The filling will be more "sticky" and easier to roll into balls for wrapping later on. Remove from heat and let it cool down completely before wrapping
Place pandan juice and the bread flour in a small saucepan. Whisk until there is no more lumps. Cook this mixture over medium heat until it is thickened, about 5 minutes or less. Remove from the heat and let it cool down completely
Make the dough:
Mix all the dry ingredients together in a mixing bowl. Make a well in the center and pour in the wet ingredients and the tangzhong. Use a dough hook attachment to knead the dough until all the crumbly dough starts to come together into one mass, it may take about 2-3 minutes for this to happen. Don't try to add any liquid. You may need to stop halfway and scrape the dough off the hook and the sides of the bowl and knead again several times
Once it comes into a dough, stop the machine. The dough will not be smooth, don't worry. Cover the dough and let it rest for 20 minutes. Do not skip this step
After the rest, turn on and knead the dough again and knead for 1-2 minutes until it is a bit smoother. Then add the salt and sugar into the dough. Continue to knead until the dough is relatively smooth. You need to stop and scrape the dough off the hook and the bowl several times during this process
Once you have a smooth dough, turn the machine back on again to knead and gradually add in the softened butter a bit by a bit. It is a REAL sticky mess again because of the butter, just keep kneading and stop halfway and scrape the dough off the hook and bowl again and continue to knead until the butter is absorbed by the dough. Don't add any flour. You will get a shiny smooth dough that is very elastic. It may take 10-15 minutes of kneading with a machine
Place this dough in a lightly oiled large bowl, cover it with a clean and damp tea cloth or plastic wrap and let it rise at a warm place for about 1 hour. The dough will really puff up, may be double in size may be closed to double.
Shape into rolls:
Lightly oil your pan, I used a 9 x 9 inch square pan and line with a parchment paper. Deflate the dough and knead a few times to push out all air. Divide into 9 equal smaller size doughs. Cover these dough balls loosely with a plastic wrap and let them rest for 15 minutes. Make sure you don't skip this part of resting the dough before shaping
Roll each ball out into a rectangle shape (don't have to be exact). Spread with about a tablespoon or so of the inti filling. Fold the two long sides up and then roll it from the bottom to top. Place the seam side down in the pan. Continue with the rest of the dough and filling. Place them next to each other. Cover with a plastic wrap
If you don't like the way I roll and fill the buns, you can just roll the dough into a circle about 4-inch in diameter and put about 1 Tbsp of filling or more and gather the side and seal. This will give you a filling that is more towards the center. I goofed up thinking I was going to get a nice swirl of the filling inside the buns LOL!
Let the shaped dough proof again for another 40 minutes or until they fill up the pan. Brush the top of the dough with egg wash. Sprinkle with some white sesame seeds or other seeds of your choice if you like
Preheat oven to 350 F and pop it into the oven (3rd rack from the top) and let it bake for the next 15-28 minutes. Remove from the oven and let them cool down in the pan for about 5 minutes and then lift the rolls out by grabbing on the parchment paper and let them cool completely on a cooling rack. Enjoy and once it's cooled down completely, wrap it up with plastic wrap and it's good for about 3 days or so (it didn't last that long in our house)