To make the tangzhong: combine ¼ cup flour and 2/3 cup milk in saucepan over medium heat. Whisk for 2-3 minutes, until thickened to a custard consistency. Remove from the heat and whisk in the remaining milk, melted butter, eggs and salt.

Combine the remaining 4 cups flour, sugar and yeast in bowl of electric mixer with dough hook attachment. Add the wet ingredients and knead for 8-10 minutes until smooth and elastic. Note: the dough should still be sticky at this stage. Using wet hands, transfer the dough to a lightly oiled bowl. Cover with a damp cloth, and leave in a warm place for 60-90 minutes, or until the dough has doubled in size.

For the filling: beat all the ingredients together until well combined. Set aside. Grease the baking dish with extra butter.

Knock the air from the dough and turn onto a floured worksurface. Roll out to a 30cm x 70cm rectangle and spread evenly with the cinnamon filling. Working from the long edge, cut the dough into 12 even strips approximately 6cm-wide. Leave the dough to rise for 10 minutes, then gently roll up each strip into a pinwheel and place cut-side up in the greased baking dish, evenly spaced. Cover with a damp cloth and return to a warm place. Leave to rise for another 30-45 minutes, until the scrolls have almost doubled in size. Meanwhile, preheat your oven to 180°C/ 160°C fan-forced.

Once risen, bake the scrolls for 25-30 minutes, or until golden brown on top and cooked through. Allow to cool.

For the frosting: beat all the ingredients together to a smooth spreadable consistency. Spread evenly over the cinnamon scrolls and serve.