In a small saucepan, whisk together the milk and flour until no lumps remain. Set the saucepan over medium heat and whisk constantly until the mixture starts to thicken into a thick paste, the consistency of mashed potato. Remove from the heat and let cool to room temperature.

In a microwave-safe measuring cup, heat milk for 20 seconds until warm but not hot. Whisk the yeast into measuring cup and let sit until foamy.

In the bowl of a stand mixer, add the bread flour, one egg, salt, sugar, and butter. Add the cooled tangzhong and the proofed yeast with milk. Attach the dough hook and mix for 30 seconds to 1 minute until a shaggy dough comes together.

Increase the speed to medium and knead for 8 to 10 minutes until the dough is strong enough to form a windowpane.

Wipe the bowl of the mixer and lightly grease with oil. Form the dough into a ball and let proof at room temperature for about 1 ½ hours or until doubled in size.

Grease a baking pan on all sides with oil and line with parchment, leaving an inch or two overhanging on the long sides.

Gently pat down the dough to expel any air and divide into nine equal portions. Shape each portion into a ball and arrange them in the baking pan.

Let the dough rise covered for about 45 minutes to 1 hour until doubled in size.

Toward the end of the final proof, preheat the oven to 350°F.

In a small bowl, whisk together the remaining egg with a teaspoon of water.

Brush the tops of the rolls with egg wash and sprinkle with flaky salt. Bake for about 20 minutes, rotating the pan halfway through.

While the rolls bake, mash the butter, garlic powder, parsley, and Parmesan until homogeneous.

Remove rolls from the oven and brush them with garlic butter. Let cool in the pan for 10 minutes before serving.