In a large mixing bowl or the bowl of a stand mixer, combine 1 ½ cups of the 3 ¼-1/2 cups all-purpose flour, 2- 0.25 oz packages each active dry yeast and 1 ½ teaspoons salt.
In a saucepan, heat ¾ cup milk, ¼ cup packed brown sugar and 2 Tablespoons unsalted butter to 110-115°F.
Add to dry mixture in mixing bowl followed by the ½ cup mashed sweet potatoes. Beat the mixture gradually increasing to high speed; beat on high 3 minutes or until smooth.
Slowly add in the remaining flour to make a stiff dough (you may not need the remaining ¼ cup of flour).
Turn out onto a floured surface and knead for 5-8 minutes, or until smooth and elastic. Alternately, use the dough hook on the stand mixer and knead the mixture 2-3 minutes, or until smooth and elastic.
Shape the dough into a ball and place in a lightly greased bowl. Cover with a clean kitchen towel and let rise in a warm, but not hot, place until doubled in size (about 45 minutes – 1 hour).
Punch down, cover again and let rest 10 minutes. Then, shape into 9 rolls. Place the rolls in a 9” baking pan.
Cover with a clean kitchen towel and let rise in a warm, but not hot, place until the rolls have doubled in size.
Bake at 375℉ for 35-45 minutes (or until an instant read thermometer reaches 190℉ when inserted into a roll).
Immediately brush with melted butter once removed from oven (optional).