In a large mixing bowl, whisk together the flour, instant yeast, sugar, and salt. Add the warm milk, egg, and melted butter. Stir until a soft dough forms.
Turn the dough onto a lightly floured surface and knead for 8–10 minutes, until smooth and elastic. The dough should feel soft and slightly tacky but not sticky.
(If using a stand mixer, knead with the dough hook on medium speed for 6–7 minutes.)
Place the dough in a lightly greased bowl. Cover and let rise in a warm place for 60–75 minutes, or until doubled in size.
Punch down the dough and divide into 8 equal portions (about 90–95 g each). Roll into smooth balls and place on a parchment-lined baking sheet. Gently flatten each one slightly.
Cover loosely and let rise again for 30–40 minutes, until puffy.
Preheat oven to 375°F (190°C).
Brush buns with egg wash and sprinkle with sesame seeds if using.
Bake for 15–18 minutes, until golden brown.
Transfer buns to a wire rack and cool for at least 20 minutes before slicing.
