Trim top and side crusts from bread, leaving bottom crust intact. Make diagonal cuts, 1 in. thick, through the bread but not through the bottom. Combine all remaining ingredients. Spread half the butter mixture between bread slices. Spread remaining mixture over top and sides of bread.
Place bread in foil boat; cover loosely with another sheet of foil. Bake at 425° for 20-30 minutes. For last 5 minutes, remove foil to allow bread to brown