Heat milk in microwave for 40 seconds or until it's warm to the touch (about 110 degrees).
Pour milk into the bowl of an electric mixer and sprinkle with yeast.
Add sugar, egg, egg yolk and melted butter. Whisk until combined.
Stir in flour and salt with a wooden spoon until dough begins to form.
Knead dough by hand on a floured surface for 10 minutes or use an electric mixer with a dough hook attachment on medium speed for 8 minutes.
If dough sticks to the counter/bottom of the bowl add an additional 2 Tbsp of bread flour and continue kneading until a soft, slightly sticky ball forms.
Place dough in an oiled bowl, cover with plastic wrap and a dry, warmed towel and let it rise for 1 hour to 1.5 hours until doubled in size.
Grease the bottom and sides of a 9-inch baking pan. Set aside.
On a lightly floured surface, roll dough with a rolling pin until it is a 15 x 12 inch rectangle.
Spread softened (not melted) butter over the surface of dough. Combine brown sugar and cinnamon and sprinkle over buttered dough then press cinnamon sugar mixture into the butter with your hands.
Using a pizza cutter or sharp knife, cut dough lengthwise into 6 strips, each measuring 2 inches wide.
Roll up the 1st strip and place in the center of your baking pan, flat side down.
Gently coil the next strip of dough around the roll in the pan, making sure the cinnamon side is facing toward the center.
Repeat the coiling process, strip-by-strip until a giant cinnamon roll takes shape.
Cover baking pan with plastic wrap and a dry, warm towel then dough allow to rise for 30 to 45 minutes.
Preheat oven to 350 degrees.
Remove towel and plastic wrap from baking pan then bake the giant cinnamon roll for 30 minutes or until the edges are slightly golden brown. Do not overbake.
Allow cinnamon roll to cool in pan for 5 minutes while you make the icing.