Preheat the oven to 400°F. Heat a 10-inch ovenproof skillet in the oven for 10 minutes.
Meanwhile, combine the cornmeal, flour, baking powder, and salt in a medium bowl and whisk to blend. Combine the buttermilk, syrup, and egg in a 2 cup measuring cup or small bowl and whisk to blend.
Using a potholder, remove the skillet from the oven. Add the butter and sage to the skillet and swirl until the butter melts and the sage sizzles. Pour the butter and sage into the egg mixture, leaving just enough butter in the pan to coat the pan. Whisk the butter into the egg mixture, and then add to the dry ingredients. Stir just until combined. Pour the batter into the skillet. Using a potholder, return the skillet to the oven. Bake the bread until brown around the edges and feels springy when pressed in the center, about 20 minutes. Let cool in the skillet at least 10 minutes. Turn out onto a platter, if desired. Serve the bread warm or at room temperature with the Maple-Molasses Butter.