Preheat the Oven: Preheat the oven to 350°F (175°C). Lightly spray a 9×9-inch metal baking pan with oil and set it aside.
Combine the Dry Ingredients: Add the finely ground cornmeal, oat flour, baking powder, baking soda, and sea salt to a large mixing bowl. Whisk until the dry ingredients are evenly combined.
Add the Wet Ingredients: Add the Greek yogurt, milk or milk alternative, melted butter, honey, and egg to the bowl with the dry ingredients.
Mix the Batter: Using a rubber spatula, stir the mixture together until the batter is combined and no streaks or lumps of dry ingredients remain.
Fill the Baking Pan: Transfer the prepared batter to the greased 9×9-inch baking pan. Tap the pan on the counter several times to help spread and level the batter.
Bake the Cornbread: Place the pan in the preheated oven and bake for 16–20 minutes, or until the top is golden and a toothpick inserted into the cornbread comes out clean. The source notes that 18 minutes was ideal in its oven.
Slice and Serve: Slice the baked cornbread into squares and serve warm with butter and honey.