In a a large measuring cup or bowl dissolve yeast in milk. Set aside to bloom for 5-7 minutes until frothy.
In a large bowl use a whisk to sift together flour, sugar and salt. Make a well in the center.
Add butter and yeast mixture to the well. 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 1/2 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 a floured surface. Turn to coat with flour working in additional flour just until the dough isn't sticky. Press into a 24x12 inch rectangle.
Spread softened butter from end to end. In a small bowl 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 13x9 inch baking pan. Arrange cinnamon rolls side by side in the skillet. 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.
Frosting: In a small mixing bowl whisk together powdered sugar, vanilla and cream. Add additional cream until it reaches desired consistency. Frost cinnamon rolls.
Serve warm or agt room temperature.