Tangzhong (starter)

5 tablespoons water
5 tablespoons whole milk
3 tablespoons 1 teaspoon King Arthur Unbleached Bread Flour

Dough
4 cups 2 tablespoons King Arthur Unbleached Bread Flour
3 tablespoons Baker's Special Dry Milk or 1/3 cup nonfat dry milk
1 3/4 teaspoons salt
1 tablespoon instant yeast
3/4 cup lukewarm whole milk
2 large eggs
3/8 cup (6 tablespoons) unsalted butter, melted

Filling
3/4 cup brown sugar
4 teaspoons ground cinnamon

Icing
2 cups confectioners' sugar
pinch of salt
2 tablespoons melted butter
1/2 teaspoon vanilla extract
2 to 3 tablespoons whole milk or cream, enough to make a thick but spreadable frosting