Makes 3 loaves.
In a large glass, stoneware or plastic bowl, using a wooden spoon, stir together starter, 2 cups warm water and 2 1/2 cups flour until well blended. Cover loosely with plastic wrap. Let stand in a warm place (85 F) at least 12 hours.
In a small bowl, sprinkle yeast over 1/4 c warm water; stir until dissolved.
In a 2-qt saucepan over low heat, heat milk, sugar, salt and 3 Tbsp butter until warm (105 - 115 F). Remove from heat, stir in yeast mixture.
Stir yeast mixture into starter mixture. Stir in 2 1/2 cups flour until well blended. Cover loosely with plastic wrap. Let rise in a warm place until almost doubled, about 45 minutes to one hour.
Stir down batter, Gradually stir in enough additional flour to make a soft dough, Turn out dough onto lightly floured surface, knead until smooth and elastic, about 5 to 7 minutes.
Divide dough into thirds, cover and let rest 10 minutes.
Shape each third into a loaf. Place each into a greased 8 1/2 x 4 1/2 x 2 1/2 loaf pan. Cover and let rise until doubled, about 45 minutes to one hour.
Bake in 375 F oven 40 minutes, or until loaves are golden brown and sound hollow when tapped. Immediately remove from pans. Brush tops of hot loaves with melted butter. Cool on racks.