Add all of the dry ingredients into the large bowl of a stand mixer and stir together.
Using a pastry cutter or a fork, cut in the butter. I find that it’s easy to do when I use a cheese grater to shred the butter first.
Add milk and discard to the bowl and knead the dough using the dough hook attachment for about 3 minutes or until you have a soft cohesive dough. Be sure to stop and scrape the sides of the bowl if necessary.
Cover the bowl with plastic wrap and leave it to rise or ferment on the counter for 2-4 hours.
On a lightly floured surface, roll the dough out into a rectangle, about 1/2 inch thick. Brush the dough with softened butter, then sprinkle with the sugar and cinnamon mixture. Cut the dough into 3-4 inch squares. The number of squares will depend on the size of your rectangle but it isn’t important.
Place the squares into a greased loaf pan, stacking them with the loaf pan tilted so that the squares are on their side and not flat on the bottom.
Bake at 350° for 40-50 minutes or until golden brown and fully cooked through (you can insert a toothpick to check for doneness). I recommend covering the top of the loaf with foil after about 20 minutes of baking so that the top doesn’t get too dark.
While it’s baking, make the icing by whisking together the powdered sugar, softened butter, and heavy cream.
Let the loaf cool and drizzle with icing.