Preheat the oven to 400°F.
Generously butter a 10-inch cast iron skillet and warm it in the oven for 5 minutes to melt the butter and to preheat the pan.
Meanwhile, whisk together the cornmeal, flour, baking powder, and salt in a large mixing bowl until thoroughly combined.
Whisk the eggs in a medium bowl until blended, then pour in the maple syrup, milk, and oil and whisk until well mixed.
Dump the wet ingredients into the dry ingredients and stir them together until the batter is smooth.
For a lighter-textured cornbread, let the batter stand for 5 minutes before pouring into the prepared skillet. For a slightly denser result, skip the rest time.
Bake at 400°F for 30 minutes, until a toothpick inserted in the center comes out clean and the top is lightly browned.
Let the cornbread cool for 10 minutes, then slice and serve with butter, jam, soup, or another dish.