Heat oven to 350°F. Coat a rimmed baking sheet with nonstick cooking spray.
Mix together brown sugar, butter and cinnamon.
Roll dough to a 12 x 10-inch rectangle. Top with sugar mixture. Starting on one long side, fold dough into thirds to enclose filling. Pinch seam tightly to seal. Tuck ends under.
Set on baking sheet, seam-side down; cover with plastic wrap. Place in a warm spot; let rise for 30 minutes, until doubled in size. Remove plastic wrap. Bake in 350°F oven for 25 minutes, until puffed and golden.
Blend confectioner's sugar and milk until smooth. Spread over still-warm loaf. Cut into slices.