1. To make the dough, combine the flour and yeast in the bowl of a stand mixer. Heat the milk, sour cream, butter, granulated sugar and salt in a medium saucepan over medium heat. Stir occasionally, until just warm, 3 minutes; you do not want it to simmer or boil. Add the milk mixture to the mixer bowl with the flour. Beat with the paddle attachment. Add the egg and beat until a dough forms. Beat for a few minutes until the dough pulls away from the edges of the bowl.
2. Remove the dough from the mixer bowl with lightly floured hands and place in a large oiled bowl to rise. Cover and let rise in a warm room until the dough has a chance to double in size. This will take about 90 minutes, depending on the temperature of the room. It may take a bit longer if the room is not so warm.
3. To make the filling, whisk together the brown sugar and cinnamon in a bowl. Coat a 10-inch (25-cm) cast-iron skillet with vegetable oil or cooking spray. Preheat the oven to 350°F (180°C) with the rack in the middle.
4. Once the dough has risen, on a lightly floured surface, roll the dough out to a
5. roughly 14 x 10-inch (35.5 x 25-cm) rectangle. Brush the dough with some of the melted butter. Make sure to coat the entire rectangle. Sprinkle the cinnamon sugar mixture evenly over the top.
6. Start to roll the dough from the long edge away from you. Continue to roll until you have a log. Seal the edge with some melted butter. Cut the log until you have about ten 1-inch (2.5-cm)-tall slices. Place the slices into the prepared skillet. Drizzle any remaining butter over the top of the rolls.
7. Bake for 30 minutes uncovered, until the cinnamon rolls are golden brown. Remove from the oven and let cool before adding the frosting.
8. While the rolls are baking, make the frosting. With the paddle attachment, beat the cream cheese, butter and pumpkin together on medium speed until smooth. Add the powdered sugar, maple syrup and pumpkin pie spice, and beat on low until just combined; increase to medium speed until you have
9. a smooth consistency.
10. Slather the frosting on top of the cooled cinnamon rolls and serve. Top with nuts, if desire