Tucking in whole fresh sage leaves as you braid the dough (which is flecked with chopped sage and thyme) makes for pretty and fragrant loaves.
Preheat oven to 350 degrees. Line 2 large baking sheets with parchment. Divide dough into 6 equal pieces. Roll each piece into a 16-inch-long, 3/4-inch-wide rope.
Braid 3 ropes together on a prepared sheet, tucking in sage leaves as you work. Pinch ends to seal; tuck under loaf. Brush with beaten egg. Drape loosely with buttered plastic wrap. Repeat with remaining dough, sage leaves, and egg wash. Let rise in a warm spot until doubled in bulk, about 55 minutes.
Bake loaves until golden brown, about 20 minutes. Brush center with butter and continue baking until outer crust sounds hollow when bottom is tapped, about 8 minutes more. Brush all over with butter. Let cool completely on a wire rack before serving.