Prepare the Roux (Tangzhong)

1. In a small saucepan, whisk together bread flour and milk. 
2. Cook over low heat, stirring constantly until it thickens into a paste. Remove from heat and let it cool completely before using.

Make the Dough

1. Mix yeast, 1 tsp of sugar (from the 25 g total) with the lukemilk in a bowl to bloom the yeast.  Stir until the yeast has dissolved.  Cover with a towel for 5 to 10 minutes or until a layer of foam forms. 
2. In the mixing bowl of a stand mixer, combine bread flour, sugar, salt, and half the beaten egg. 
3. Add bloomed yeast mixture, cooled Tangzhong and mix until a shaggy dough forms.
4. Knead using a stand mixer (or by hand) until the dough starts to come together.
5. Gradually add the softened butter, kneading until fully incorporated. Continue kneading until it passes the windowpane test (when you can stretch the dough thinly enough to let light pass through).
6. Lightly oil a bowl, place the dough inside, and roll it around to coat the surface. Cover and let it proof in a warm place until it doubles in size (about 1–2 hours).

Shape the Rolls

1. Once the dough has doubled in size, sprinkle some flour on top of it and gently press to release excess gas.
2. Transfer onto a lightly floured surface, keeping the sticky side up.
3. Shape it into a smooth ball, then weigh the dough (total weight should be around 344 g) and divide it into 6 equal portions (around 57 grams / portion). 
4. Form each portion into a ball by pulling and tucking the sides underneath, then cover them all with a tea towel to rest for 15 minutes.
5. Roll each piece into an oval shape, about 6 inches long.
6. Use a dough scraper or knife to cut thin lines halfway through the dough (should look like fingers on a hand or teeth on a comb).
7. Spread 1 tsp sambal oelek and 2 tsp grated Parmesan on the uncut half.
8. Roll the dough up from the filled side, pinching the cut dough to seal the ends.
9. Place rolls onto a lined baking tray, cover with a tea towel, and let them proof for another 45–60 minutes until puffy.

Final Touches & Bake

1. Preheat the oven to 180°C fan (400°F).
2. Mix the reserved beaten egg with milk to make the egg wash.
3. Brush a thin layer over the buns and sprinkle extra Parmesan on top.
4. Bake for 16–18 minutes until beautifully golden brown.  For your reference, mine took 17 minutes. 
5. Let them cool slightly before transferring to a wire rack.
6. Serve them warm!