In the bowl of a stand mixer fitted with the paddle attachment, combine the all-purpose flour, whole wheat flour, instant yeast, and kosher salt. Mix on low speed until well combined.
In a small saucepan, heat the mashed baked sweet potato, whole milk, unsalted butter, honey, and vanilla extract over medium heat. Stir occasionally until the butter is melted and the mixture reaches a temperature between 120°F (49°C) and 130°F (54°C).
Slowly add the warm sweet potato mixture to the flour mixture in the stand mixer. Beat on low speed until the ingredients are combined, which should take about one minute.
Switch to the dough hook attachment and mix the dough on medium speed until it becomes smooth and elastic, about 12 to 13 minutes.
Once the dough has formed, turn it out onto a very lightly floured surface. Shape it into a smooth round.
Lightly oil a medium bowl, place the dough in it, and turn to coat the top with oil. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm, draft-free place until doubled in size, which should take about 45 minutes to 1 hour.
While the dough rises, spray a 9-inch round cake pan with cooking spray.
After the dough has doubled, punch it down gently to release air bubbles, and turn it out onto a lightly floured surface. Divide the dough into 9 equal portions and shape each portion into a smooth round. Place them in the prepared pan.
Cover the dough again and let it rise in a warm place until it doubles in size again, about 35 to 45 minutes.
Preheat your oven to 350°F (180°C). Once preheated, brush the tops of the rolls with the beaten egg and sprinkle with Simply Organic Seeds if desired.
Bake the rolls in the preheated oven until they are deep golden brown and an instant-read thermometer inserted in the center reads 200°F (93°C), which should take about 25 to 30 minutes.
Let them cool in the pan for 5 to 10 minutes before serving. Enjoy the aroma!
