1. Prepare rolls: In a small saucepan, heat milk and 2 tbsp butter just until warm and butter is almost melted, stirring constantly.
2. In large mixer bowl, combine pumpkin, sugar and salt. Add milk mixture and beat with an electric mixer until well mixed. Beat in egg and yeast. In a separate mixing bowl, combine flours. Add half of flour mixture to pumpkin mixture. Beat mixture on low speed for 5 minutes, scraping sides of bowl frequently. Add remaining flour and mix thoroughly (dough will be very soft). Turn into lightly greased bowl, then grease surface of dough lightly. Cover and let rise in warm place until doubled, about 1 hour.
3. Punch dough down. Turn onto floured surface. Knead a few turns to form a smooth dough, sprinkling with enough additional flour to make dough easy to handle. On lightly floured surface, roll dough into 12x10-inch rectangle.
4. In a small bowl, combine brown sugar and cinnamon. Brush surface of dough with melted butter. Sprinkle with brown sugar mixture. Beginning with long side of dough, roll up jelly-roll style. Pinch seam to seal. With a sharp serrated knife, gently cut roll into twelve 1-inch slices. Place rolls cut-side-up in greased 9-inch-square baking pan.
5. Cover and let rise until nearly doubled, 30 to 45 minutes.
6. Preheat oven to 180°C. Bake rolls about 20 minutes, or until golden. Remove from pan to baking paper lined wire rack. Cool 10 to 15 minutes.
7. While rolls are cooling, prepare icing: Mix butter, icing sugar and vanilla in a bowl. Add hot water 1 tbsp at a time until the glaze reaches desired consistency. Drizzle over the top of the rolls