Pour the warm milk into a large mixing bowl.
Add the yeast and granulated sugar.
Stir gently and let rest for 5 minutes until foamy.
Whisk in the egg, fine sea salt, and melted butter until smooth.
Add 3 cups of the flour and stir until a shaggy dough forms.
Turn the dough out onto a lightly floured surface.
Knead the dough for 5 minutes, adding additional flour only if needed.
Continue kneading until the dough is soft, smooth, and slightly tacky.
Shape the dough into a ball.
Place the dough in a lightly greased bowl and cover loosely.
Let the dough rise for 60 to 75 minutes until doubled in size.
Gently punch down the dough.
Roll the dough into a 12-inch circle on a lightly floured surface.
Brush the surface evenly with the softened butter.
Fold the dough in half, then fold in half again to form a quarter circle.
Roll the dough gently back into a 12-inch circle.
Cut the circle into 12 equal triangular wedges.
Roll each triangle from the wide end toward the tip.
Curve each roll slightly to form a crescent shape.
Place the shaped crescents on a parchment-lined baking sheet, spacing them apart.
Cover loosely and let rest for 20 minutes.
Preheat the oven to 375°F while the rolls rest.
Bake the rolls for 11 to 13 minutes until lightly golden.
Remove from the oven and brush with melted butter, if desired.
Sprinkle lightly with flaky salt, if using.