Warm the milk and butter together over the stove or in the microwave until butter is just melted. You want the mixture lukewarm (105°F (41°C)-115°F (46°C)), not scorching hot. Set aside.
Whisk the pumpkin puree, sugar, nutmeg, and salt together in a large bowl. Whisk in the warmed milk/butter, egg, and yeast until combined. Using the dough hook or paddle attachment on low speed mix in 1 cup of flour. Mix for 1 minute, scraping down the sides of the bowl as needed. Add 1 and 2/3 cups more flour and beat for 1 more minute.
Keep the dough in the mixer and beat on low speed for an additional 3 minutes or knead by hand on a lightly floured surface for 3 minutes.
Lightly grease a large bowl with oil or use nonstick spray. Place the dough in the bowl, turning it to coat all sides in the oil. Cover the bowl with plastic wrap. Allow the dough to rise in a relatively warm environment for 2 hours or until doubled in size.
Grease the bottom and sides of a 9-inch square baking dish.
Punch down the dough to release the air. Place dough on a lightly floured work surface and using a lightly floured rolling pin, roll dough into a 10×14 inch rectangle. Make sure the dough is smooth and evenly thick. If the dough keeps shrinking as you roll it out, stop what you’re doing, cover it lightly, and let it rest for 10 minutes to relax the gluten. When you return to the dough, it should stretch out much easier.
Spread softened butter evenly on top of the rolled-out dough. Combine the brown sugar, cinnamon, PBFit powder and spices into a small bowl. Sprinkle all over the top. Roll it up tightly. Using a very sharp knife, cut into 10-12 even rolls. Arrange rolls in the prepared pan.
Cover the rolls tightly and allow to rise until doubled in size, about 1 hour.
Preheat the oven to 350°F.
Bake rolls for about 22-28 minutes or until they are lightly browned on top. After about 15 minutes, tent a piece of aluminum foil over the top of the pan to prevent the tops from browning too quickly. Remove the pan from the oven and place the pan on a wire rack for about 10 minutes as you make the icing.
Using a handheld or stand mixer fitted with a paddle or whisk attachment, beat the softened cream cheese in a medium bowl on medium speed until smooth. Add the maple syrup and milk and beat on high until smooth. Add the confectioners’ sugar and PBFit powder and beat on medium speed until creamy. Spread on warm cinnamon rolls.
Cover leftover frosted or unfrosted rolls tightly and store at room temperature for up to 2 days or in the refrigerator for up to 5 days.