In a large bowl, whisk together the cornmeal, flour, salt, baking powder, baking soda and cinnamon. In a medium bowl, whisk together the milk, eggs and syrup until smooth. Stir the wet ingredients into the dry ingredients until moistened through.
Heat the oven to 375 degrees Fahrenheit with a rack in the middle of the oven. Place the stick of butter in a 10 to 12-inch cast iron skillet or 9-inch square baking dish and place in the oven to melt for 5 to 10 minutes.