In large bowl, stir 2 cups of the flour, 1/3 cup sugar, the salt and yeast with a wooden spoon until well mixed. In 1-quart saucepan, heat water and 1/3 cup butter over medium-low heat, stirring frequently, until very warm (120°F to 130°F). Add to flour mixture. Beat with electric mixer on low speed 1 minute, scraping sides of bowl occasionally, until smooth. With a wooden spoon, stir in enough of the remaining flour, 1 cup at a time, until dough is soft, leaves side of bowl and is easy to handle (dough may be slightly sticky).