For tangzhong, mix flour and milk in a small saucepan until smooth. Place over medium heat and cook, whisking continuously until thickened. Place into a small bowl and refrigerate to cool.
Place warm milk and yeast into the bowl of a stand mixer and set aside to activate for 10 minutes.
Add tangzhong, flour, sugar, egg and salt and mix on low speed with a dough hook until combined.
Add butter, piece by piece, and mix until combined.
Increase speed to medium and knead for 10 minutes.
Transfer to a lightly oiled bowl, cover with cling film and set aside for one hour or until doubled in size.
Meanwhile, make the filling. Mix butter, sugar and cinnamon in a small bowl until smooth.
Knock back dough on a lightly floured bench and roll out into a 24x30cm rectangle.
Using a palate knife, spread the filling thinly up to the edges.
Roll into a log from the shorter side. Cut into 6 equal rounds and place rolls into a 20x25cm baking paper lined tray.
Cover loosely with cling film and set aside to prove for 30 minutes.
Meanwhile, preheat oven to 180 ° C and make the icing. Place butter into a small saucepan and heat over low/med heat. Cook until it turns nut brown. Pour into a small bowl and refrigerate until solid.
Beat brown butter in a stand mixer until creamed. Add cream cheese and beat on high until smooth. Add icing mixture and beat on low until combined.
Bake rolls on the lowest shelf for 20-25 minutes, covering with alfoil if they become too coloured.
Allow to cool in the tray before icing generously.
