In a large bowl, whisk together the flour, sugar, and salt. Make a well and add the starter, milk, and melted butter. Stir into a shaggy dough, then knead for 8 to 10 minutes until smooth and elastic.

Place the dough in a buttered bowl, cover, and rest 30 minutes. Perform one set of stretch and folds, then let bulk ferment at room temperature for 4 to 5 hours until doubled.

Butter a 9x13-inch pan. Deflate the dough, divide into 12 portions, and shape into tight balls. Arrange in the pan, cover, and proof for 2 to 3 hours until doubled and puffy.

Preheat oven to 375°F (190°C). Brush tops with melted butter and bake for 20 to 25 minutes, until deeply golden and hollow sounding when tapped.

Brush hot rolls with more butter, cool in the pan for 5 to 10 minutes, then pull apart and serve warm.