Combine the warm milk, 1 tablespoon of the sugar, and the yeast in a large mixing bowl and set aside until foamy, 5 to 10 minutes.

Lightly oil the inside of another large mixing bowl, and set it aside.

Add the flour, remaining 3 tablespoons sugar, salt, butter, and the 2 whisked eggs to the yeast mixture, and using a wooden spoon, stir to blend well. When the dough begins to clump, add the potato and stir together until the dough forms a mass.

Transfer the dough to a lightly floured work surface and knead until it comes together and is smooth and springy, 2 to 3 minutes (dust your hands and work surface with flour for easier handling). Then transfer the dough to the oiled bowl.

Turn the dough so the entire surface is lightly oiled, cover the bowl with plastic wrap, and let it sit in a warm, draft-free place until the dough has doubled in size and small bubbles appear on the surface, about 11/2 hours.

Lightly grease a baking sheet with oil.Transfer the dough to a lightly floured work surface; the dough will be sticky, so dust your hands as necessary to ease handling. Punch down the dough and then knead it several times to form a ball.

Using a dough scraper or a knife, divide the dough into 8 equal portions. Shape each portion into a roll by slightly cupping your hand over the dough and rolling the dough in a circular motion on the counter (if the dough is sticky, dust it with a little flour). After shaping them, place the rolls, seam side down, on the prepared baking sheet; stagger the rolls, leaving about 2 inches of space in between. Lightly brush the rolls with oil.

Cover the rolls loosely with plastic wrap and let them rise in a warm, draft-free spot until doubled in size, about 1 hour.

Preheat the oven to 375°F. In a small bowl, whisk together the remaining egg and the heavy cream. Brush the rolls with the egg mixture, and transfer the baking sheet to the oven. Bake until the rolls are golden brown and the internal temperature registers 200°F when tested with an instant-read thermometer, 20 to 25 minutes. Remove from the oven and set on a wire rack to cool.

The cooled bread can be wrapped in plastic wrap and stored overnight at room temperature or frozen for up to 3 months.