Heat oven to 425°F. Line a baking sheet or grease a cast-iron skillet.
Whisk flour, sugar, baking soda, salt, and caraway in a large bowl.
Cut in the cold butter until the mixture looks like coarse crumbs.
Fold in raisins to coat them with the dry mixture.
Make a well and pour in buttermilk. Stir with a fork until shaggy.
Turn dough onto a lightly floured surface. Gently knead 6–8 times to bring together.
Shape into a 7-inch round and set on the prepared pan. Slash a deep X on top.
Bake 38–42 minutes until golden and 200°F inside. Tent with foil if it browns early.
Brush the hot loaf with melted butter. Cool 15 minutes before slicing.