• Please note that I have included two methods below for tangzhong making and dough kneading using either Thermomix or conventional bread machine so do take note of the sub-headings.

[THERMOMIX] Tangzhong & Dough Kneading

• To make tangzhong, place 20g high protein flour and 100g water/milk in mixing bowl, cook for 1min/75°C/spd 2 and let stand for 10-15 minutes until temperature lowers down to 37°C.
• Whilst your tangzhong is cooling down, prepare Chocolate Paste by mixing cocoa powder and milk in a separate small bowl. Set aside.
• Moving back to your mixing bowl, once temperature hits 37°C, add milk, whipping cream, sugar, egg and yeast, then mix 30 sec/spd 2.
• Add remaining 270g high protein flour, milk powder, salt and butter then mix 30secs/spd 6. Proceed to knead 4 min.
• Weigh out 330g of dough to pastry mat or greased bowl, shape into ball then let rise, covered loosely with clingwrap/damp towel until doubled in size (approx. 45-60 minutes). 
• Add chocolate paste into remaining dough. Mix 15 secs/spd 6, then knead for 30 secs. Transfer chocolate dough to pastry mat or another greased bowl, shape into ball and let rise, covered loosely with clingwrap/damp towel until doubled in size (approx. 45-60 minutes).

[CONVENTIONAL] Tangzhong & Dough Kneading

• Prepare tangzhong by mixing flour in water and whisk together in a pot, ensuring the mixture is well combined with no lumps. Cook over medium-low heat, stirring consistently to prevent burning and sticking while you cook.
• The mixture will gradually become thicker. Once you notice that some “lines” appear in the mixture for when you stir with the spoon, it’s done. Your tangzhong is ready.
  
• Transfer into a clean bowl. Cover with a cling wrap sticking onto the surface of tangzhong to prevent it from drying up. Let cool.
• You can pre-make the tangzhong ahead of time and store it chilled in the fridge for a few days. If you've chilled your tangzhong, ensure to return it at room temperature first before using.
• Whilst your tangzhong is cooling down, prepare Chocolate Paste by mixing cocoa powder and milk in a separate small bowl. Set aside.
• Add all ingredients into breadmaker; first the wet ingredients (tangzhong, egg, milk, cream), then followed by the dry ingredients (in order of sugar, salt, flour, milk powder, yeast).
• Select "dough" mode and let knead until all ingredients come together, usually I let it knead for approximately 8-9 minutes.
• Then add in the butter, continue kneading until the dough is smooth and elastic. My breadmaker's dough kneading cycle is 23 minutes. During the last 4-5 minutes, pause the machine, weigh out 330g of dough to pastry mat or greased bowl.
• Add chocolate paste into the remaining half of dough in the mixing bowl and continue to knead until the cycle is complete.
• Whilst your chocolate dough is kneading during this 5 minutes, shape your milk dough into a ball then let rise covered loosely with clingwrap/damp towel until doubled in size (approx. 45-60 minutes). 
• Repeat the same steps with your chocolate dough - transfer chocolate dough to pastry mat or another greased bowl, shape into ball and let rise, covered loosely with clingwrap/damp towel until doubled in size (approx. 45-60 minutes).

Dough Shaping

• After both doughs have doubled in size, punch down to deflate. Divide milk dough into 5 equal portions weighing approx 65-67g each and roughly roll into a round shape. As for chocolate dough, divide into 4 equal portions also weighing approx 65-67g each and roll into round shape. Let rest, covered for 10-15 minutes so the dough will be easier to handle.
• Shape each portion into tight round balls and place in a greased/lined 8" square pan alternately such as the below picture:
  
• Let dough rise for its 2nd round of proofing, until double in size. This takes another 35-40 minutes depending on the weather. The best temperature for 2nd round proofing is 38C, humidity 85%. I usually heat up a cup of water in the microwave for 60 seconds then proceed to leave my dough, covered with a cloth/cling wrap, inside the microwave to rise. 
• During last 15 minutes, preheat oven to 180°C.
• Lightly sift some flour over dough and bake at 180°C for 15 mins until golden brown.
• Remove from oven, and let cool for 5 minutes. Remove bread from pan (handle with care as bread will be very soft) and transfer onto a wire rack to let cool completely.