Preheat oven to 375 degrees F. Place a 10-inch cast iron skillet or Dutch oven in the oven.

In a large bowl, combine flour, sugar, salt and baking soda.

In a large glass measuring cup or another bowl, whisk together buttermilk and butter. Pour mixture over dry ingredients and stir using a rubber spatula until a wet, sticky dough forms.

Working on a lightly floured surface, gently knead the dough a few times, shaping the dough into an 8-inch round, about 1-inch thick, adding additional flour as needed.

Place dough into the prepared skillet. Using a sharp knife or bread lame, cut a 1/2-inch deep “X” into the top of the bread; brush with additional buttermilk and sprinkle with rolled oats.

Place into oven and bake until golden brown and the bottom of the bread sounds hollow when tapped, about 35 minutes.

Serve warm.