Make the tangzhong: in a small pot, whisk together the bread flour, water and milk. Cook on medium whisking frequently until the mix turns into a thick paste, about 5 minutes.
In a cup or small bowl, combine the warm water and yeast and stir to help it dissolve. Let it set for a few minutes.
In the bowl of a stand mixer fitted with a dough hook, add the yeast mixture, the tangzhong and the remaining dough ingredients. Knead on medium speed for about 20 minutes. Place the dough in an oiled bowl and cover with plastic wrap. Set it in the fridge to rise overnight or on the counter for a couple of hours until it has doubled in size.
Make the filling and shape the rolls:
Place the butter in a frying pan and cook on medium heat. It will melt, then sizzle and sputter. Once it goes quiet transfer it to a heatproof bowl making sure to scrape in the brown specks. Mix in the brown sugar, vanilla, salt, cinnamon and nutmeg and set the mix aside to cool.
Grease and line a 13×9 cake pan with parchment paper.
Roll out the dough (straight from the fridge) onto a well floured surface to about the size of a half cookie sheet (18×13 inches). Spread the filling onto the dough and roll it up into a log from the shorter side. Using unwaxed dental floss, slice the log into 12 rolls and arrange them in the prepared pan. Cover the pan with a tea towel and let them rise until they are puffy and when you press them, the dough doesn’t immediately spring back (about an hour, more if your kitchen is cold).
Preheat the oven to 350 F. Bake the rolls for 30 minutes, until they are slightly browned.
When the rolls are cool, make the glaze: whisk together the powdered sugar, heavy cream (use more if the glaze is too thick), pink gel food coloring (or substitute raspberry juice), salt and vanilla. Spread over the rolls and top with sprinkles. Sprinkles not optional.