Line a 5x9x3" (approximate) with parchment paper. Set aside.
Allow dough to completely thaw.
In a bowl, combine sugar and cinnamon and whisk to mix completely.
Transfer mixture to a large plate and set aside.
Flour a cutting board and place your loaf on it.
Make 6-8 deep cuts into the loaf, being careful not to cut all the way through.
Thoroughly brush the loaf with the melted butter on all sides.
Transfer cinnamon sugar to a plate and roll in cinnamon mixture, pressing well into the deep cuts.
Place in the prepared loaf pan and set in a warm place to rise for 30 minutes.
Preheat oven to 300.
Bake for 30-40 minutes, until top is golden brown.
If bread is fully cooked tapping on bottom will make a hollow sound.
Place powdered sugar in a small bowl.
Slowly add milk, while stirring, to achieve desired consistency.
While bread is still warm, remove from pan and drizzle with glaze.