Combine the flour, salt, sugar, matcha powder and instant yeast in a bowl of a stand mixer. Make a well in the center. Add in all wet ingredients: milk, egg and tangzhong. Fit the dough hook attachment on your stand mixer and begin mixing on medium speed and knead until your dough comes together and then add in the butter and continue kneading. Keep kneading until the dough is smooth, not too sticky on the surface and elastic. I kneaded the dough for about 18-20 minutes. Each mixer may vary.

When the dough is ready, you should be able to take a chunk of dough and stretch it to a very thin membrane before it breaks. When it does break, the break should be form a circle. (Here's a picture I took from another attempt without the matcha flavor)

Knead the dough into a ball shape. Take a large bowl and grease with oil. Place dough into greased bowl and cover with a wet towel. Let it proof until it’s doubled in size, about 40 minutes.

Combine the flour, cocoa powder, salt, sugar and instant yeast in a bowl of a stand mixer. Make a well in the center. Add in all wet ingredients: milk, egg and tangzhong. Fit the dough hook attachment on your stand mixer and begin mixing on medium speed and knead until your dough comes together and then add in the butter and continue kneading. Keep kneading until the dough is smooth, not too sticky on the surface and elastic. I kneaded the dough for about 18-20 minutes. Each mixer may vary.

When the dough is ready, you should be able to take a chunk of dough and stretch it to a very thin membrane before it breaks. When it does break, the break should be form a circle.

Knead the dough into a ball shape. Take a large bowl and grease with oil. Place dough into greased bowl and cover with a wet towel. Let it proof until it’s doubled in size, about 40 minutes.

Transfer doughs after they have doubled in size to a clean surface. Divide each flavor of the dough into the dough into two equal portions. Knead into balls. Cover with cling wrap, let rest for 15 minutes.

For each ball of dough: Roll out each portion of the dough with a rolling pin into an oval shape. Take one end of the dough and fold to meet the middle of the oval. Take the other end and fold to meet on top. (here are some pics from a previous attempt making this bread without the flavors)

Flip dough over with the folds facing down,and flatten dough with rolling pin. Roll out the dough until it forms a thin rectangle. Repeat with the rest of the dough balls, so that you should end up with two matcha rectangles and two chocolate ones. Make sure they are about the same size.

Place a piece of chocolate dough on top of the matcha one (or you can reverse the order) and begin rolling up the dough along the wide/long side of the rectangle, so you will end up with a long skinny roll rather than a short and fat one. Place each of the rolls into 9 x 5 bread pans lined with parchment paper and put a piece of plastic wrap over the rolls. Let them rise until double the size, approximately another 40 minutes.

Beat an egg and brush egg mixture on top to create shiny eggwash finish.