To make the sponge dough, Mix Bread Flour (50 gram), Instant Dry Yeast (1/2 teaspoon), Granulated Sugar (1/4 teaspoon), and Water (32 gram) in a mixing bowl and knead with your hand for few minutes until smooth and shiny. Roll into a ball and place in a greased bowl. Cover with cling film and let it prove for 1 hours in a warm and dark place.
Place into the refrigerator and use the next day. Then 30 minutes before using, take out the sponge dough from refrigerator to return to room temperature.
For the main dough, line the baking trays with parchment paper.
Put the Salt (1 teaspoon), Bread Flour (300 gram), Instant Dry Yeast (1 teaspoon), Brown Sugar (20 gram), Milk Powder (30 gram), Butter (35 gram), Egg (40 gram), Water (135 gram) and sponge dough into the bowl of stand mixer. Using the dough hook on a stand mixer, knead until the dough comes together and is beginning to become elastic and tacky but not sticky.
Let the dough rise in a warm place for 60 minutes or until double in size in a large greased bowl, covered with cling film or kitchen towel.
Punch down the dough to release the air. Transfer the dough to a clean floured surface then divide into 6 equal portions. Roll out each dough with a rolling pin into rectangle shape. Roll up the dough like a Swiss roll until a long log is formed. Place all dough in prepared baking pan.
Let it rise for another 50 - 60 minutes or until double in size in a warm and dark place.
Then 15 minutes before baking, preheat the oven to 180 degrees C (350 degrees F).
Brush with egg wash made of Egg (10 gram) and Water (1 teaspoon) and sprinkle with Old Fashioned Rolled Oats (to taste). Bake for 30 minutes, or until golden brown.
Remove bread to cool on rack.