Microwave the whole milk in 30-second increments until it reaches 110 degrees or is warm to the touch.

Pour the warm milk into a large bowl of a stand mixer fitted with a dough hook.

Add yeast and 1 tablespoon of granulated sugar to the milk and whisk to combine. Let it sit until foamy, about 5 minutes.

Add the room temperature egg, kosher salt, 4 tablespoons of melted butter, and the remaining tablespoon of granulated sugar. Beat on medium speed until well combined, about 30 seconds.

Add 1 cup of flour and beat on medium speed until combined, about 30 seconds.

Scrape down the sides of the bowl with a rubber spatula, then add the remaining 2 1/4 cups of flour. Beat on medium speed until the dough comes together and pulls away from the sides of the bowl, about 1 minute.

Continue to beat, scraping the dough hook when needed, until the dough is smoother and more elastic, about 3 minutes more.

Lightly grease a large bowl with oil. Scrape the dough into the bowl and toss to coat it in oil.

Cover the bowl with plastic wrap or a clean kitchen towel. Let it rise in a warm place until it doubles in size, about 1 hour.

Punch down the risen dough and divide it into 12 pieces, each about 70 grams. Shape each piece into smooth round balls and arrange them in the prepared pan.

Cover with plastic wrap or a clean kitchen towel and let rise in a warm place until puffed, about 1 hour.

Arrange a rack in the lower third of the oven and preheat to 350 degrees.

Bake the rolls, rotating halfway through and tenting with foil if they are browning too quickly, until the tops are golden brown, about 25 to 30 minutes.

Brush the rolls with the remaining 2 tablespoons of melted butter and sprinkle with flaky sea salt.