In the bowl of a mixer, use the paddle to combine the flour, sugar, and yeast and mix on low speed briefly. Add the salt and mix for about 10 seconds.
4 ⅔ cup (600 grams) bread flour, ¼ cup (50 grams) granulated sugar, 2 ¼ teaspoons instant yeast, 2 teaspoons salt
Add the mashed sweet potato, eggs, and the starter. Mix on low speed. When the dough starts to come together, switch to the dough hook. If the dough doesn't come together, add an additional tablespoon of milk at a time.
2 large eggs, roux starter, 1 cup (240 grams) mashed sweet potato
Increase the speed to medium and add the butter, one or two small cubes at a time. It should take a few minutes to finish adding the butter. Knead for about five to seven minutes more, scraping the dough if it sticks to the bottom of the mixer. At the end of kneading, the dough should be soft and tacky but not sticky.
8 tablespoons (113 grams) unsalted butter
Shape the dough into a boule, cover the bowl with plastic wrap, and let it rise in a warm place until doubled in size, about one and a half to two hours.
Lightly grease a 9 by 13 inch baking pan.
Divide the remaining dough into 15 equal-sized pieces, and roll each portion into a ball (see the link below and in the main post for how to shape dinner rolls). Place the bread rolls in the pan so they are equally spaced and not touching.
Cover the pan with plastic wrap, and let the dough rise again in a warm, draft-free location until doubled in size, about 2 hours.
Thirty minutes before baking, preheat the oven to 350°F.
Bake for about 20 to 22 minutes until lightly browned and the internal temperature is 190°F. Check after about 10 minutes and lightly cover with aluminum foil if the rolls are browning quickly.
Serve warm or at room temperature.