Japanese Milk Bread/ Hokkaido Milk Bread- Bánh Mì Ngọt Kiểu Nhật

This recipe is based on Cooking NYtimes, Christine's recipes, and Food52.
This lofty, feathery bread is good enough to eat plain or with a schmear of butter or even better in sandwich.

For the starter (Tangzhong):
   1/3 cup/45 g all-purpose flour or bread flour, plus extra for rolling and shaping the dough
   1/2 cup water 120 ml)
   1/2 cup milk (120m)
For the dough:
   5 cups/650 g all purpose or bread flour
   1/2 cup/105 g sugar
   2 tsp/7 g active dry yeast
   1 tsp/4 g salt
   1 cup/ 240 ml warm milk,105-110 oF, plus extra for brushing
   2 eggs
   2 Tbs/8 g milk powder (optional)
   4 Tbs/60 g unsalted butter, soften at room temperature, plus extra for buttering pans and bread.
Two 9x5x2.5 inch pan.

1. Make the starter:  In a small saucepan, whisk flour, milk and water until smooth.  Bring it to a simmer  over medium high heat, stir constantly.  When the mixture starts curdle at the bottom.  Reduce the heat to medium low and continue stirring constantly.  When the lines/tracks appear on the bottom of the pan, remove it from heat. Continue stirring a few more minutes off heat and scrape it into a small bowl, cover and let it cool down to room temperature.
2. Make the dough:  In the bowl of a stand mixer fitted with a dough hook, combine flour, sugar, salt, milk powder and yeast.  Mix a few seconds.  In a medium bowl, whisk eggs, starter, and milk together.  Make a well in the dry ingredients and pour in all wet ingredients.  Stir  until the mixture forms a loose, shaggy dough.  Then turn the mixer on low speed #2, knead about 5 minutes.  Add butter and knead about 15-20 minutes until the dough is smooth and springy/elastic.  This is a sticky dough, slightly sprinkle your hands with flour to prevent sticking but try not to over flour.  Cover the bowl with plastic wrap and let the dough rise in a warm place until double in size about 1-2 hour.  
3. Punch the dough down and use your hands or flexible dough scraper to take it out on a floured surface.  Divide the dough into 8 portions.  Roll each into a ball, cover and let rest 15 minutes.  Roll each ball into an oval shape. Fold one third from top edge into the dough and press down with the fingers.  Fold one third from bottom edge to the middle and press down again.  Turn the seam down and roll it out about 12 inches/30 cm long.  Turn the seam upward and roll into a cylinder.  Place into the pan with seam down. Repeat with remaining dough, 4 rolls for each pan. Cover and let the dough proof again t about 40 minutes to 1 hours until nearly double. After about 40 minutes, preheat oven to 350 oF.  The dough is ready to bake when the indentation of a finger bounced back slowly but invisible and it should peek over the edge of the pan.  Brush top with milk.
4. Bake at bottom rack until golden brown and puffed about 25-30 minutes for dark pans/ 30-40 minutes for glass or light aluminum pans. The core temperature should reach 198 oF.  
5. Let cool in the pan on wire rack for 10 minutes.  Then remove the bread from the pan and let it cool on wire rack for at least 1 hour before sliding or enjoy when it is still warm.  Store in an airtight container and freeze it if needed.