Preheat oven to 425℉. Grease (1) 10-inch cast iron skillet with vegetable oil and place in the oven while it preheats.
While pan and oven heat, mix the chopped cranberries and the sugar in a small bowl. Set aside.
In a large bowl, whisk together the cornmeal, flour, baking powder and salt.
In a medium bowl or a large measuring cup, whisk together the melted butter, eggs, buttermilk and pumpkin puree.
Add the sugared cranberries and the wet ingredients to the dry ingredients. Stir until just combined.
Pour batter into the preheated pan. Bake for 15-18 minutes, or until golden and a toothpick inserted into the center comes out clean.
Notes
If using frozen cranberries, there is no need to thaw them first.You can use a smaller cast-iron skillet, such as an 8-inch or 9-inch, but keep in mind that you may need to adjust the baking time.