Step 1: Prepare the Dough, In a large bowl, combine warm milk, sugar, and yeast. Let it sit for a few minutes until the yeast becomes active. Add sourdough discard, egg, melted butter, salt, and flour. Mix until a soft dough forms.
Step 2: Knead the Dough, Knead the dough by hand for about 8–10 minutes or use a stand mixer until it becomes smooth and elastic. The dough should be soft and slightly sticky.
Step 3: Let the Dough Rise, Place the dough in a lightly greased bowl, cover it, and allow it to rise in a warm place until it doubles in size, usually about 1–2 hours.
Step 4: Shape the Rolls, Divide the dough into equal portions and shape each piece into a smooth ball. Place the rolls in a greased baking dish, leaving a little space between each roll.
Step 5: Second Rise, Cover the shaped rolls and let them rise again for about 30–45 minutes until they become puffy.
Step 6: Bake the Rolls, Bake in a preheated oven at 375°F (190°C) for 20–25 minutes or until the tops are golden brown. Brush with melted butter after baking for extra softness and flavor.