On low heat, in a pan, combine water, milk, and flour. Stir until it thickens into a paste.

In the bowl of a stand mixer with a dough hook, add whipping cream, milk, sugar, yeast, flour, softened butter, tang zhong, egg, and salt.

Knead on medium speed until a soft dough ball forms, then knead on high for 10 mins. The dough should look smooth and tacky but not sticky.

Line a baking tray with parchment paper.

Divide the dough into 6 equal pieces.

Take one and shape it into a sphere. Place it on a surface and gently roll it into a log with one hand. Then, using both hands, roll the ends to create a slight football shape. Arrange the shaped dough on the baking tray with space between each.

Brush on scrambled egg wash to the surface.

Repeat with the remaining dough.

Allow the buns to rest in the turned-off oven with the pilot light on until they double in size, which typically takes 1.5 to three hours. The proofing time may vary depending on the climate in your region; buns may proof faster in the summer than in winter. For best results, place a bowl of boiling water inside the oven on the top rack over the baking tray. This method creates a warmer and more humid environment.

Preheat the oven to 325°F / 163°C.

When the oven comes to full temperature, bake on the center rack for 12 mins. Then move the tray to the top rack for the last 5 mins.

Take the buns out of the oven and let them cool completely at room temperature.

In a pot briefly heat the whipped cream to 80°F.

In a tall bowl, combine softened butter, sugar, and salt. Mix.

Add the whipping cream and beat with the bowl covered to avoid splashes until stiff peaks form.

Transfer the mixture into a piping bag equipped with a large pastry tip, ensuring to expel any excess air. Securely close the top by either winding it around your finger or using a rubber band.

Brush melted butter onto the bun surfaces, ensuring even coverage.

Dip in coconut flakes.