Prepare the sweet potato: Place the chopped sweet potato in a medium saucepan and add enough water to cover. Bring to a boil over high heat, then reduce the heat to medium-high and boil until the sweet potato is very soft and tender, about 10–12 minutes. Drain off the water, then mash the sweet potato as well as you can—a few small lumps are okay. Measure 1 cup (230g) of mashed sweet potato to use in the dough and set aside to slightly cool. (Do not use more than 1 cup in your dough. Discard or eat any leftover sweet potatoes.)
Proof the yeast: Whisk the warm milk, yeast, and 2 tablespoons of honey together in the bowl of your stand mixer. Cover and allow to sit for 5 minutes. *If you do not own a stand mixer, you can do this in a large mixing bowl and in the next step, mix the dough together with a large wooden spoon/silicone spatula.
Make the dough: Add the remaining honey, eggs, butter, mashed sweet potato, salt, and 1 cup (125g) flour to the yeast mixture. With a dough hook or paddle attachment, mix/beat on low speed for 1 minute. Stop and scrape down the sides of the bowl with a silicone spatula, then add the remaining flour. Beat on medium speed until the dough comes together and pulls away from the sides of the bowl, about 3 minutes. If the dough seems too wet to a point where kneading would be impossible, beat in more flour 1 tablespoon at a time until you have a workable dough. Dough should be soft and a little sticky, but still manageable to knead with lightly floured hands.
Knead the dough: Keep the dough in the mixer fitted with a dough hook and beat on low speed for an additional 5 full minutes or knead by hand on a lightly floured surface for 5 full minutes. After kneading, the dough should feel soft and smooth. Poke it with your finger—if it slowly bounces back, your dough is ready to rise.
1st Rise: Lightly grease a large bowl with oil or nonstick spray. Place the dough in the bowl, turning it to coat all sides in the oil. Cover the bowl and allow the dough to rise in a relatively warm environment for 1–2 hours or until double in size.
Grease a 9x13-inch baking pan.
Shape the rolls: When the dough is ready, punch it down to release the air. Divide the dough into 20 equal pieces, about 65–75g each (doesn’t need to be exact!). Shape each piece into a smooth ball. Arrange in prepared baking pan.
2nd Rise: Cover shaped rolls and allow to rise until puffy, about 30 to 45 minutes.
Adjust oven rack to a lower position and preheat oven to 350°F (177°C).
Bake the rolls: Bake for 25 minutes or until golden brown on top (internal temperature if taken with an instant-read thermometer should be 190°F), rotating the pan halfway through. If you notice the tops browning too quickly, loosely tent the pan with aluminum foil. Remove from the oven, brush with melted butter and sprinkle with flaky sea salt and allow rolls to cool for 15 minutes before serving.
Cover leftover rolls tightly and store at room temperature for up to 3 days, or in the refrigerator for up to 1 week.