Peel and dice a potato. Place it in a saucepan of water and bring to boil. Then reduce the heat to medium and cook the potato until tender. Drain the liquid and mash the cooked potato.
Measure 1 cup of firmly packed mashed potato and transfer it to a bowl. Add 2 tablespoons unsalted butter and mix until the butter is melted and absorbed. Let the mixture cool off for 10 minutes.
In a separate mixing bowl, add ¼ cup whole milk and a large egg (both room temperature) and give it a whisk.
In a stand mixer bowl, add dry ingredients (2 ¼ cups all-purpose flour, 2 teaspoons instant yeast, 1 teaspoon salt, 1 teaspoon granulated sugar) and give it a stir.
Add wet ingredients, and using your hands, mix until combined. Then add mashed potato/butter mixture and mix it again with your hands.
Using a dough attachment, knead the dough on low speed for about 5-8 minutes. If it gets too sticky, add more flour one tablespoon at a time.
When done, add a tablespoon olive oil and grease the dough from all the sides. Cover the bowl with plastic wrap or a towel and let rise for 1 hour or until doubled in size.
When ready, deflate the dough and transfer it to a lightly floured surface. Divide the dough into 12 equal pieces and form them into balls.
Place the balls on a baking sheet with parchment paper, cover with plastic wrap and let sit for 30-40 minutes.
When ready, brush the tops with egg wash and sprinkle with sesame seeds.
Bake at 425°F for about 15 minutes or until the tops are golden in color.