Preheat oven to 350° F.

Grease a 10 inch cast iron skillet with non-stick spray or softened butter.

In a medium bowl, whisk together the flour, cornmeal, baking powder, salt, and baking soda. Set aside.

In a large bowl beat together the butter and both sugars, until light and fluffy, using a stand or handheld mixer.

Add the eggs and vanilla and beat until thoroughly combined.

On low speed, add half of the flour mixture and mix until no dry spots remain. Then add half of the buttermilk and mix until combined. Then repeat with the remaining flour mixture and the rest of the buttermilk. Do not overmix.

Fold the cranberries evenly into the batter using a rubber spatula.

Spread the batter evenly into the prepared skillet and bake on the middle rack for 50-55 minutes. Or until a toothpick inserted into the middle of the cake comes out with a few moist crumbs.

Let cool in pan for at least 30 minutes before serving.