Prepare the tangzhong. Mix together, 15g flour, and 80g of milk in a small saucepan. Put the saucepan over medium-low heat and whisk constantly. When the whisk starts to leave trails where you can see the bottom of the pan, it is done. Transfer to a small bowl and allow to cool.
In the bowl of your stand mixer with your dough hook attached, add flour, baker's dry milk, yeast, salt, sugar, egg, and milk. Mix on low until a shaggy dough forms.
Stop the mixer, cover the bowl for 10 minutes and allow the dough to rest.
After 10 minutes, one tbsp at a time, add softened butter. Let butter fully incorporate into the dough until adding the next.
Knead dough on low until dough is very smooth and no longer sticking to the sides. Anywhere from 10-30 minutes.
When dough is ready, place in a lightly greased bowl and cover. Allow dough to rise for 1-2 hours or until doubled in size.
Prepare a 8.5x4.5" or 9x4 pullman loaf pan with parchment.
Punch down the dough and remove it from bowl. Divide dough into 4 equal parts.
Shape dough piece into a rectangle and roll out into a long skinny rectangle. The width of the dough should be about the width of your pan. Roll up the dough into a log.
Place seam side down into the prepared pan. Repeat with remaining pieces of dough.
Cover the pan and allow dough to rise again for about another 45 minutes-1 hour, or until dough has puffed significantly to about twice in size.
About 20 minutes (more or less depending on your oven) into the second proof, preheat your oven to 350°F.
When loaf is ready, place on the middle rack of your oven and bake for about 25 minutes or until the top is golden brown. A thermometer inserted into the bread should read 190°F.
Remove the bread from the pan to a wire cooling rack within 5-10 minutes. Let bread cool at least 30 min before eating. Store in an airtight container. Enjoy!
