In a large bowl, mix 1 ½ cup flour and yeast; put aside. Add pumpkin, milk, sugar, 2 tablespoon butter and salt in a saucepan, heat and stir until warm. Add to flour-yeast mixture along with egg. Beat on low speed for 30 seconds, then high for 3 minutes. Stir in enough remaining flour to make a stiff dough. Lightly floured surface and knead dough until smooth and elastic, about 6-8 minutes. Place dough in a greased bowl, turn to grease both top and bottom of dough. Let covered dough rise until doubled, about 1 hour. Roll into a 12-inch x 10-inch rectangle. Melt remaining butter; brush on dough. Combine brown sugar and cinnamon; sprinkle over dough. Roll dough starting with the longer side. Cut into 12 slices. Place rolls in a greased 13-inch x 9-inch x 2-inch baking pan. Cover and let rise until doubled. Bake at 375 degree for 20-25 minutes or until golden brown. Cool on a wire rack. How to make frosting: In a pan melt butter; stir in brown sugar and milk. Cook and stir over medium-low heat for one minute. Add salt and ¼ cup powdered sugar; beat until well blended. Add more powdered sugar if needed. Spread over rolls. Make 1 dozen rolls.