Dissolve sugar and yeast in warm milk in a large bowl; let stand 5 minutes. Stir in 1 tablespoon butter. Lightly spoon flour into dry measuring cups; level with a knife. Add 3 cups flour and salt to yeast mixture; stir until a soft dough forms. Turn dough out onto a floured surface. Knead until smooth and elastic (about 8 minutes); add enough of remaining 1/4 cup flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in size. (Gently press two fingers into dough. If indentation remains, the dough has risen enough.) Punch dough down; cover and let rest 5 minutes.
Roll dough into a 14 x 7-inch rectangle on a lightly floured surface. Roll up rectangle tightly, starting with a short edge, pressing firmly to eliminate air pockets; pinch seam and ends to seal. Place roll, seam side down, in an 8 x 4 1/2-inch loaf pan coated with cooking spray. Lightly coat surface of dough with cooking spray, and cover; let rise in a warm place (85°), free from drafts, 30 minutes or until doubled in size.
Preheat oven to 400°.
Uncover loaf; drizzle surface of loaf with remaining 1 tablespoon butter, gently spreading with a pastry brush. Cut a (1/4-inch-deep) slit lengthwise down center of loaf using a sharp knife.
Bake at 400° for 30 minutes or until the bread is browned on bottom and sounds hollow when tapped. Cool on wire rack.