Warm your milk to 110 degrees F by either microwave or stove. Use a thermometer to know it's ready.
1 cup whole milk, warm
If using active dry yeast, stir it into the warm milk with 1 Tbsp sugar and let sit 5–10 minutes until foamy.
2 ¼ tsp instant yeast, 2 tbsp granulated sugar
If using instant yeast, skip this and move on to the next step.
In a large bowl (or stand mixer with dough hook), combine milk, yeast, sugar, egg, and softened butter. Mix until the egg and sugar and combined with the rest of the liquid ingredients.
1 large egg, ¼ cup unsalted butter
Add flour and salt. Mix until a soft dough forms. It should be slightly tacky but not sticky. Add more flour if needed (up to 1/4 cup).
3 & ¼ cups bread flour, 1 ½ tsp salt
Knead by hand or mixer on medium speed for 8–10 minutes until smooth, elastic, and stretchy.
Place dough in a greased bowl, cover, and let rise in a warm spot until doubled, about 1–1 ½ hours.
Punch down dough and divide into 15 equal pieces (about 50-55g each). Shape into smooth balls. Arrange evenly in a greased 9x13 pan (3 rows of 5).
Cover and let rise again until puffy, almost doubled, about 30-45 minutes.
Preheat oven to 350°F ). Bake rolls for 17-18 minutes, until golden brown on top and cooked through.
Brush warm rolls with melted butter and sprinkle with flaky salt (if desired).
3 Tbsp unsalted butter, Flaky salt