Brown 2 tablespoons of butter over medium-high heat. Remove from heat and add room temperature milk, return to stove and heat through. Poor milk and butter into the stand mixer. Allow to cool to a warm temperature. Add yeast and 1/4 cup of sugar. Allow to proof. Add pumpkin, salt and 1 cup of flour. Stir using hook attachment until combined. Add 1/2 cup of flour at a time. Knead for 6 minutes, until dough is smooth, elastic, and slightly sticky. And extra flour 1 tablespoon at a time if needed.
Allow dough to rise in a lightly oiled bowl (in a warm place) for 60-90 minutes. Dough should double in size.
While rising, brown 2 tablespoons of butter. Mix 1 cup of granulated sugar and pumpkin pie spice. Grease and flour a 9x5 loaf pan and set aside.
Once dough has doubled in size, punch it down and flop out onto a clean floured surface. Knead with hands for 1-2 minutes. Roll dough into a 20x12 inch rectangle. Brush dough with butter. Sprinkle with sugar mixture and press into dough with palms of hand. Cut the rectangle into 6 even strips. Lay strips on top of each other and cut each strip into 6 even pieces. Stack strips vertically into the loaf pan. Cover the pan with a clean towel and let rise for 30-45 minutes.
While rising, preheat oven to 350 degrees. After rising in pan, bake for 30-40 minutes or until top is a very deep golden brown.
For Glaze, heat the butter, milk, and brown sugar in a small saucepan. Bring to boil then immediately remove the pan from the heat and stir in the rum and powdered sugar.