Place dough in a large bowl of a heavy-duty mixer fitted with a paddle. Add remaining yeast, water, salt, butter and 1 cup bread flour. Beat at medium speed 3 minutes, or until smooth. Add remaining flour at low speed, 1/2 cup at a time, until soft dough is formed. Dough will just clear sides of bowl. (Process can also be done by hand in a large bowl.)
Switch to a dough hook and continue mixing about 3 to 4 minutes, adding flour 1 Tablespoon at a time. (If kneading by hand, turn dough out onto a lightly floured work surface and knead 5 to 7 minutes, adding flour 1 Tablespoon at a time as necessary.) Dough should barely hold its shape. Place in a greased bowl, turning once to coat. Cover with plastic wrap and let rise in a warm place until tripled, about 2 hours.
Gently deflate dough, turn out onto a lightly floured work surface and form into a round ball or oblong loaf. Roll lightly in flour and place on a baking sheet sprinkled with semolina flour. (Or, place dough in a greased 12" x 5" x
Preheat oven to 475° for at least 30 minutes. Make a slit in top of loaf with a serrated knife. Bake at 475° for 10 minutes, 400° for 15 minutes, and 325° for 20 to 30 minutes. Loaf is done when slightly domed and browned. Cool on a rack. Makes 1 large loaf.
Note: Dough can also be shaped into flatbread, breadsticks or rolls.