1. In large bowl, combine sugar, salt, yeast, and 1 cup flour. In 1-quart saucepan over low heat, heat butter or margarine and 2/3 cup milk until very warm (120° to 130°F.). Butter or margarine does not need to melt.
2. With mixer at low speed, gradually beat liquid into dry ingredients just until blended. Increase speed to medium; beat 2 minutes, occasionally scraping bowl with rubber spatula. Beat in eggs and 1 1/2 cups flour to make a thick batter; continue beating 2 minutes, occasionally scraping bowl. With wooden spoon, stir in 2 1/2 cups flour to make a very soft dough.
3. Turn dough onto well-floured surface and knead until smooth and elastic, about 10 minutes, working in more flour (about 1/2 cup) while kneading. Shape dough into ball; place in greased large bowl, turning dough to grease top. Cover; let rise in warm place (80° to 85°F.) until doubled, about 1 hour.
4. Punch down dough. Turn dough onto lightly floured surface; cut in half; cover and let rest 15 minutes. Grease 2 cookie sheets.
5. Shape dough into two 6-inch round loaves. Place each loaf on a cookie sheet; cover; let rise in warm place until doubled, about 1 hour.
6. Preheat oven to 350°F. Cut 3 long slashes on top of each loaf. With pastry brush, gently brush loaves with some milk. Bake 35 minutes or until golden and loaves test done. Remove loaves from cookie sheets; cool on wire racks.