Add the water, flour, and milk to a small saucepan over medium low heat. Stir continually until it thickens into a paste. Remove from heat and set aside.

In the bowl of a stand mixer add the yeast, milk, and sugar. Allow the mixture to set about 5 minutes until the yeast becomes frothy.

To the mixing bowl add the tangzhong, egg, flour, and salt. Mix on low speed until the dough comes together completely.

Once the dough has come together, add in the butter, one tablespoon at a time until it is all completely incorporated. The dough should be smooth and come somewhat free from the sides of the bowl. If the dough is too sticky, add additional flour one tablespoon at a time, I ended up adding 2 tablespoons.

Place the dough into an oiled bowl and cover it with plastic wrap, or a damp towel. Allow the dough to proof until it is double in size, about 1 hour.

While the dough is proofing, prepare a loaf pan by spraying it with non-stick cooking spray.

When the dough has doubled in size, dump it out onto a lightly floured surface and divide it into 3 equal pieces.

Flatten each section out into a rectangle, fold the sides in, lengthwise, toward the center to create a skinnier rectangle, flatten them a bit further until they are about the width of your bread pan.

Roll each long rectangle into a log and fit them together in a line into the prepared bread pan, keeping the seams on the bottom of the pan.

Cover the formed loaf and allow it to proof until it is peaking just above the bread pan, 45 minutes to 1 hour.

Whole the loaf is proofing, preheat the oven to 350 degrees fahrenheit.

Once the loaf is ready to bake, make the egg wash by whisking the egg white and water together.

Brush the egg wash over the loaf and bake the loaf for 25-30 minutes. The bread should be golden brown and temp out to 190 degrees fahrenheit.

Remove the bread from the pan and allow it to cool for at least 10 minutes before serving.