1 3/4 cups buttermilk
1 large egg
4 1/4 cups all-purpose flour (plus more for kneading)
3 Tbsp. sugar
1 tsp. baking soda
1 tsp. salt
5 Tbsp. unsalted butter, cold and cubed
optional: 1 cup raisins
1. Preheat oven to 400 degrees. Line a baking sheet with parchment paper, use a seasoned 10 or 12" cast iron skillet or grease a 9" cake pan or pie dish. Set aside.
2. Whisk the buttermilk and egg together. Set aside. Whisk the flour, sugar, baking soda and salt together in a large bowl. Cut in the butter using a pastry knife, a fork with your fingers. Work the dough until coarse crumbs. Stir in raisins. Pour in the buttermilk mixture. Gently fold the dough together until dough is too stiff to stir. With floured hands on a lightly floured surface, work the dough into an 8 or 9" round loaf. Knead the dough for about 30 seconds or until the flour is moistened. If the dough is too sticky, add a little more flour.
3. Transfer the dough to the prepared pan or skillet. Using a very sharp knife, score an "X" into the top of the loaf. Bake until bread is golden brown and the center appears cooked through, about 45 minutes. Loosely cover the bread with aluminum foil if you notice heavy browning on top.
4. Remove bread from oven and cool for 10 minutes. Then transfer to a wire rack. Serve warm, at room temperature or toasted. Cover and store the bread at room temperature for 2 days or in the refrigerator for up to 1 week.