Pre-heat oven to 425 F.
Lightly grease an oven-safe skillet (cast iron is perfect) or baking sheet (the dough may spread a little more) with the cooking spray or some softened butter.
In a medium bowl, whisk together the buttermilk and egg and then set aside.
In a large bowl, whisk together the flour, sugar, baking soda, and salt. You can whisk with a fork for about 30 seconds, and you'll be set.
Cut the chilled butter into cubes with a sharp knife.
Using a pastry cutter, or two forks or knives, or your fingers (working quickly), cut the butter into the flour mixture. Continue to work the dough until the butter begins to resemble the size of peas.
Now fold in the raisins with a wooden spoon.
Make a well in the center of the dry ingredients and pour in the buttermilk mixture.
Gently fold the dough together with your wooden spoon until all pockets of flour are absorbed into the batter.
With floured hands, work the dough into a ball. The dough will be sticky and stiff.
Turn the dough out onto a floured surface and knead the dough for about 30 seconds. If the dough is just too sticky to work, then add a little more flour. Don't over knead! Very important!
Transfer the dough to the prepared skillet or pan.
Using a sharp knife, score a large 'X' on the top.
Bake until the bread is golden brown and the center is cooked through, about 45 minutes.
If the bread appears to be browning too much, then add a piece of aluminum foil over the top about halfway through baking.
Remove skillet/pan from oven and allow bread to cool for 10 minutes.
Transfer to a wire rack.
Slice and serve warm or at room temperature with softened butter and desired toppings.