Preheat oven to 400 degrees. Grease or line a pan with parchment paper or a silicone mat. This can be a baking sheet, cake pan, cast iron skillet or Dutch oven (uncovered.)
In a small bowl, whisk together egg and buttermilk. Set aside.
In a large bowl, combine flour, sugar, baking soda, and salt. Cut in butter, then stir in raisins. Add buttermilk mixture and fold together into a crumbly dough.
Pour out onto a lightly floured surface and knead until the flour has just been incorporated. Form dough into a loaf and place into your prepared pan. Score the top of the bread with a large "X" about 1/2-inch deep.
Bake until golden, about 45 to 55 minutes, until the internal temperature reaches 195 degrees. Remove from oven and allow to cool for 10 minutes before removing from pan to a wire rack.
Store at room temperature for 2 days or in the refrigerator for a week. Bread may also be frozen whole or in slices.