In a a large measuring cup or bowl, dissolve yeast in milk. Set aside to bloom for 5-7 minutes.
In a large bowl using a whisk, sift together flour, sugar and salt. Make a well in the center. Add butter and yeast mixture. Mix through, adding egg while mixture is still loose. Mix well.
Using an electric mixer fitted with a dough hook, knead the dough for 5 minutes or until it pulls away from the side of the bowl. If the dough is too sticky, add additional flour 1 Tbsp at time, up to ½ cup. Alternately, knead the dough by hand for 5 minutes on a lightly floured surface.
Grease the sides and bottom of a clean bowl. Transfer dough to bowl. Cover with a damp towel and let sit for 1 hour or until doubled.
Punch down dough. Turn out onto floured surface and turn until coated with flour working in additional flour just until the dough isn't sticky. Press into a 24 x 12 inch rectangle.
Spread softened butter from end to end. Mix together granulated sugar, cinnamon and nutmeg. Sprinkle evenly over butter.
Using floured fingers begin rolling from widest edge ending seam side down. Use dental floss or a sharp knife to cut into 24 even pieces.
Butter the bottom and sides of a 12 inch cast iron skillet or a 13 x 9 inch baking pan. Place cinnamon rolls side by side. Cover with damp cloth and let rise 1 hour or until doubled.
Preheat oven to 350°F. Uncover cinnamon rolls. Bake for 30 minutes or until puffed and golden.
To make the frosting: In a small mixing bowl whisk together powdered sugar, vanilla and cream. Add additional cream until it reaches desired consistency. Frost cinnamon rolls.