Before you begin, allow the butter to reach room temperature.
In the bowl of a stand mixer, place the flour and at three corners, add the salt, sugar, and crumbled yeast (ensure the yeast does not immediately mix with other ingredients).
Add the eggs and knead with the dough hook on medium speed (speed 4) for 15 minutes until the dough is smooth.
Gradually incorporate the butter and continue kneading for another minute.
On a floured surface, shape the dough into a ball and place it in a floured bowl. Cover and let rise at room temperature for 3 hours, or until it has doubled in size.
Turn the dough onto the work surface and fold it several times to ‘punch it down.’ It’s normal for the volume to decrease.
Return the dough to the bowl and refrigerate for 30 minutes. The dough will rise again.
Roll out the dough into a large rectangle. Mix brown sugar and cinnamon, then sprinkle over the dough. Roll up the dough to form a log and cut into 2 cm thick slices.
Place the slices close to each other in a buttered and floured baking mold.
Let the dough rise one last time until doubled in size, about 30 minutes.
Preheat the oven to 210°C. Brush the rolls with a beaten egg, reduce the oven temperature to 180°C, and bake for 20-30 minutes.
Mix icing sugar with an egg white gradually to achieve a thick royal icing texture. Thin with a little milk and add vanilla.
Drizzle the glaze over the cooled rolls and sprinkle lightly with cinnamon.