Preheat the oven to 350 degrees F. Lightly spray a 9x9 metal baking pan with oil and set aside.
In a large mixing bowl, add the cornmeal, oat flour, baking powder, baking soda, and sea salt. Whisk to combine.
Add the Greek yogurt, milk, melted butter, honey and egg to the bowl. Use a rubber spatula to stir together until there are no streaks or lumps of dry ingredients.
Transfer the cornbread batter to the prepared 9x9 baking pan. Once transferred, tap the pan on the counter several times to spread and level the batter.
Place in the oven and bake for 16-20 minutes (18 was perfect for my oven), or until the cornbread is golden on top and can be pierced with a toothpick and come out clean.
Slice the cornbread and serve warm with butter and honey.