Half an hour before making these cinnamon rolls, grate the butter and store it in the freezer.
Heat the oven to 218C / 425F and grease a round or square baking pan.
For the dough: In a large bowl, add flour, sugar, baking powder and salt. Mix well.
Add grated butter to the flour; mix with a wooden spoon. Add the cold milk and mix only until the dough comes together.
Cut a piece of wax paper and flour it generously. Put the dough on the wax paper, and with floured hands, stretch into a rectangle, to 1 centimeter thick or half an inch. (Or you can use a floured pin for rolling).
Filling: In a small bowl, mix brown sugar, flour and cinnamon. Brush melted butter on top of the dough. Leaving an inch on one of the sides without butter.
Sprinkle the cinnamon mixture over the butter.
With the help of the wax paper, start rolling the dough on the longest side (leaving the side without butter for last) and pinching the ends at the same time.
Cut the rolls into 8 equal portions and put them in the prepared baking pan. (If desired, brush the tops with melted butter).
Bake for 20 minutes, or until golden brwn and firm to the touch.
For the drizzle: In a small bowl, mix all the ingredients. It needs to be thick.
Remove the cinnamon rolls from the oven and immediately drizzle icing all over. Serve hot.