Preheat oven to 400ºF (205ºC) and prepare parchment-lined 10-inch cast iron skillet.
In a large mixing bowl, whisk together flour, baking soda, salt and pepper. Using a box grater, grate the cold butter into the flour then toss everything together with your hands until the pieces are evenly distributed.
Pour in buttermilk and stir or mix by hand just until ingredients start to come together. Fold in cheddar and keep turning the dough until it starts to look a little sticky and stringy.
Transfer dough to a floured surface and use floured hands to shape it into a ball. Score the top of the loaf with an ‘X’ to allow even heat distribution.
Transfer to skillet and bake for 35-40 minutes until golden and it sounds hollow when you tap on the top. Remove from oven, transfer to wire cooling rack and let cool for at least 10 minutes before slicing.