In a small saucepan, add the milk and flour. Cook for about 1 minute over medium heat until the mixture has thickened and resembles thick pudding.

Place the mixture into a small bowl, cover it with plastic wrap so it touches the surface, and leave to cool down to room temperature, or until just lukewarm.

In the bowl of a stand mixer fitted with a dough hook attachment (or use a hand mixer with hook attachments and a large bowl), add the flour, yeast, sugar, salt, milk, egg, and the tangzhong mixture. Knead on medium-low for 2-5 minutes or until the dough has formed and doesn’t stick to the walls of the bowl. It should be sticky to the touch.

Then, add the butter one tablespoon at a time and knead on medium until fully incorporated. Remove the dough from the hook once or twice and scrape the sides and the bottom of the bowl during the process. This will take up to 7 minutes.

When all butter is in, knead for 10-12 minutes on medium until it pulls away from the sides of the bowl and you can stretch a small piece of it into a square, creating a film thin enough for light to pass through (windowpane test). The dough won’t stick to your hands anymore and it will look hydrated, silky, and smooth.

When the dough has risen and is jiggly, knock it down and place it on a working surface. If it sticks to the surface, dust it with a little bit of flour.

Grease an 8" by 5" (20cm by 13cm) loaf pan with butter.

Divide the dough into 4 even parts.

Roll one piece of the dough into an oval or rectangular shape. Then, fold the right and left thirds over the center and gently press to seal.

Roll it up and seal the seam by pinching. Repeat with the rest of the dough.

Place all 4 rolls in the prepared loaf pan, seam side down. Cover with a kitchen towel and proof for 40 mins at room temperature or until well-risen and jiggly.

Meanwhile, preheat the oven to 350F (180C).

When the dough has risen, brush with an egg wash made by whisking the egg with milk. Bake in the lowest third of the oven for 20 minutes. Then, rotate the pan and cover it loosely with a piece of foil. Bake for an additional 10 minutes or until the internal temperature is 190F (88C). The top should be a deep golden brown color and the bread should sound like it’s hollow inside when you tap on it.

Remove from the loaf pan onto a cooling rack right away and let it cool down before serving.