Preheat oven to 40 degrees F; line a sheet pan with parchment paper.
In a medium bowl, whisk together buttermilk, egg, and baking soda; set aside.
Fit a food processor with the metal blade, and process the flour, sugar, baking powder, and salt until just combined, about 5 seconds; add butter and process until the mixture resembles coarse cornmeal, another 15 to 20 seconds.
Transfer mixture to a large bowl and stir in raisins and caraway; make a well in the center of the dough and pour in the buttermilk mixture.
Combine, with a rubber spatula or wooden spoon, until a wet dough forms; divide in two equal portions.
On a floured work surface, form each portion into a round loaf, about 5 inches in diameter (actually it will be a gloppy mess).
Place each round on the prepared baking sheet, leaving several inches between loaves and sides of pan to allow for spreading.
Using a sharp knife or a pastry cutter, cut each round into 5 equal wedges (known as scoring); sprinkle with flour to give the loaves a "rustic" look.
Bake for 20 minutes, then reduce heat to 375 degrees F and continue baking until loaves are golden brown on the top and bottom, about 15 to 20 minutes more.
A toothpick inserted should come out clean; cool on wire racks and serve either warm or room temperature.