Combine Water (135 gram), Instant Dry Yeast (3/4 teaspoon) and Brown Sugar (3/4 teaspoon) in a mixing bowl. Mix in Bread Flour (210 gram) and knead with your hands for a few minutes, until smooth and shiny. Roll into a ball and place in a greased bowl. Cover with cling film and let rise for 1 hour in a warm and dark place.
After 1 hour, place dough into the refrigerator for at least 8 hours or up to 16 hours. Before using, take the sponge dough out of the refrigerator and return to room temperature.
Whisk the Large Egg (1). Set aside 40 grams for the dough. Set aside the remainder to use as an egg wash.
Put Salt (1 1/2 teaspoon), Bread Flour (215 gram), Instant Dry Yeast (3/4 teaspoon), Brown Sugar (2 1/2 tablespoon), 40 grams of whisked egg, Milk (80 gram), Milk Powder (2 tablespoon), Butter (30 gram), Cream (100 gram) and sponge dough torn into a few pieces into the bowl of stand mixer. Using the dough hook, knead until the dough comes together, becoming elastic and tacky but not sticky, around 12-15 minutes at medium speed.
After kneading, divide dough into 2 equal portions. Transfer one portion to a bowl. Leave the other portion in the bowl of the stand mixer and sift in Matcha Powder (1 2/3 tablespoon). Knead again at medium speed until well mixed.
Place the doughs in a large greased bowl, covered with cling film or a kitchen towel. Let rise in a warm place for 1 hour, or until double in size.
Punch down each dough to release the air. Transfer the plain dough to a clean floured surface and divide into 2 equal portions. Shape each plain dough into a long log, about 25cm. Roll out each log with a rolling pin into a long rectangle shape, about 45 by 10 centimeters. Repeat with the matcha dough.
Spray water on the plain dough and place the matcha dough over the plain dough. Press with your palm to make sure both layers stick together. Spray some water on the matcha dough and roll it up tightly, starting from the shorter side until a log is formed. Pinch to seal the seams.
Place the dough in a loaf pan lined with parchment paper. Let it rise for another 45 minutes-1 hour, or until double in size.
Brush top of dough with egg wash and sprinkle with Black Sesame Seeds (to taste). Bake at 190 degrees C (375 degrees F) for 25-30 minutes, or until golden brown.
Remove bread from oven and let cool on rack. Serve and enjoy!