In a large saucepan, combine the 3/4 cup buttermilk,1/4 cup vegetable oil and 1/4 cup brown sugar. Warm the mixture to 105-115°F - do not allow it to boil or go above this amount. Sprinkle 1/4 ounce active dry yeast over the surface of the liquid and allow it to sit for 5 minutes. It should start to look foamy.
Once yeast has proofed, stir in 3/4 cup pumpkin puree until combined.
Combine 2 cups of the 2 1/2 cups bread flour (reserving the remaining amount) with the 1/2 teaspoon pumpkin pie spice. Add it into the saucepan and stir well to mix all of the ingredients. Knead the dough for about 5 minutes until the texture becomes more elastic and smooth. Cover the saucepan with a dish towel and set in a warm place free of any drafts for 1 to 1 1/2 hours. *see note.
After 1 to 1 1/2 hours, the mixture should be very puffy and at least doubled in size. Combine the remaining flour with 1/2 teaspoon baking powder, 1/4 teaspoon baking soda, and 1/4 teaspoon salt and sprinkle the mixture over the dough. Mix until well combined. Add additional flour, as needed, in order to just barely handle the dough without it sticking to your hands.
Preheat the oven to 375°F. Heavily grease two 8 inch cake pans with butter.
Turn out the dough onto a floured surface and press it into a rectangular shape. Use additional flour if it is still too sticky. Roll the dough into a large rectangle that's about 3/4 inch thick.
For the filling:
Drizzle 4 tablespoons melted butter over the dough and spread it all over the surface of the dough.
In a small bowl, mix together 1/4 cup brown sugar, 1/4 cup granulated sugar, and 1 teaspoon pumpkin pie spice. Sprinkle this mixture all over the surface of the dough, covering all the melted butter. Add 3/4 cup pumpkin spiced pumpkin seeds in a thin layer.
Roll the dough into a large log and pinch the end seam to seal. Use a sharp knife to cut the log in half, one for each cake pan. Cut each log into 6-9 pieces, depending on how tall you want your cinnamon rolls and place them in the buttered cake pans. Loosely cover with towel and allow to rise for 20 minutes.
Bake in preheated oven until the rolls are nice and golden brown around the edges, about 15 to 18 minutes.
For the frosting:
In the bowl of your stand mixer with the paddle attachment, cream together 4 ounces softened pumpkin flavored cream cheese and 2 tablespoons softened butter until light and fluffy, about 5 minutes. Add 1 cup powdered sugar and 1 teaspoon vanilla, then blend until smooth. Thin with additional vanilla or milk, if desired.
Frost the rolls when they come out of the oven so that they are hot and the frosting will partially melt.
Notes
To help my dough rise in a cold house, I found it best to preheat my oven to 200°F. Once it reached temperature, I turned it off, and cracked the door to release some heat, and once it cooled to a nice warm temperature, I set the dough inside. I kept the door cracked while the dough was in there. Ideally you want a space that is 78-80°F for the dough to rise.