Dissolve yeast in 1/2 cup warm water in large mixing bowl, and set aside.
Combine flour, brown sugar, salt, and spices. Add 1/2 cup flour mixture to yeast mixture, stirring well. Gradually add an additional 1/2 cup flour mixture and 1/4 cup warm water to yeast mixture; stir well. Repeat procedure with warm water and 5 cups flour mixture, reserving remaining flour mixture. Stir in sweet potatoes and butter (dough will be sticky.)
Turn dough out onto a lightly floured surface; knead, adding reserved 1 cup flour mixture, 1 tablespoon at a time. Knead for 10 to 15 minutes or until dough is smooth and elastic.
Place dough in a greased bowl, turning to grease top. Cover, and let rise in a warm place (85°), free from drafts, for 1 hour or until doubled in bulk.
Punch dough down, and divide in half; shape each into a loaf. Place in two well-greased 9- x 5- x 3-inch loaf pans. Cover, and let rise in a warm place (85°), free from drafts, for 30 minutes or until doubled in bulk. Bake at 425° for 30 minutes or until loaves sound hollow when tapped.
Oxmoor House Homestyle Recipes