Combine the flour, salt, sugar and instant yeast in a bowl of a stand mixer. Make a well in the center of the ingredients and place one of the eggs, milk, and tangzhong in it. Fit the dough hook attachment on your stand mixer and knead on medium speed until your dough comes together. Add the butter and continue kneading. Keep kneading until the dough is smooth, not too sticky on the surface and elastic. I kneaded the dough for about 18-20 minutes. Each mixer may vary.

When the dough is ready, you should be able to take a chunk of dough and stretch it to a very thin membrane before it breaks. When it does break, the break should form a circle.

Transfer the dough to a clean work surface. Divide the dough into four pieces of equal size and form them into balls. Cover the dough balls with plastic wrap and rest them for 15 minutes.

Roll out each portion of the dough with a rolling pin into an oval shape. Take one end of the dough and fold to meet the middle of the oval. Take the other end and fold to meet on top. Flip dough over with the folds facing down, and flatten dough with rolling pin.

Flip dough over so the folds face up. Sprinkle raisins across the dough and use a rolling pin to press the raisins into the dough. Roll the dough up. Place each of the rolls into the bread pan and cover the pan with plastic wrap until the rolls double in size, approximately 40 minutes.

Preheat the oven to 325°F. Beat the other egg in a small bowl. Remove the plastic wrap and brush the top of the rolls with the egg wash. Bake the loaf for approximately 30 minutes.