In a large mixing bowl, combine cornmeal and boiling water. Stir until smooth. Let cool to lukewarm.
Add molasses, butter, and salt to the cornmeal mixture. Stir to combine.
In a small bowl, dissolve yeast in warm water. Let stand until creamy, about 10 minutes.
Add yeast mixture to the cornmeal mixture. Stir in flour, one cup at a time, until a soft dough forms.
Turn dough onto a floured surface and knead until smooth and elastic, about 10 minutes.
Place dough in a greased bowl, turning once to grease the top. Cover and let rise in a warm place until doubled, about 1 hour.
Preheat oven to 375°F (190°C). Punch down dough and shape into a loaf. Place in a greased loaf pan. Cover and let rise until doubled, about 30 minutes.
Bake in preheated oven for 40 minutes, or until the top is golden brown and the loaf sounds hollow when tapped.
Remove from pan and cool on a wire rack.