Warm milk and butter together until butter melts. Ensure it’s lukewarm, not hot.
In a mixing bowl, whisk pumpkin puree, sugar, nutmeg, and salt. Add milk mixture, egg, and yeast. Mix well.
Gradually add flour until a soft, slightly sticky dough forms.
Knead for 5 minutes by hand or mixer until dough passes the windowpane test.
Place in a greased bowl, cover, and let rise for 2 hours or until doubled.
Roll dough into a 10×14 inch rectangle. Spread butter and sprinkle spice-sugar filling evenly.
Roll tightly and cut into 10–12 even pieces. Arrange in a greased baking dish.
Cover and let rise again for 1 hour.
Bake at 350°F (177°C) for 22–28 minutes, covering with foil after 15 minutes if browning too fast.
Beat cream cheese, maple syrup, and milk. Add powdered sugar (and cinnamon if using). Spread frosting over warm rolls.