Preheat oven to 400℉.
Whisk together the buttermilk and egg.
In a separate bowl, stir together the dry ingredients.
In the bowl with the flour mixture, cut in the cold, cubed butter using either your fingers, a fork, or a pastry cutter until it starts to resemble a coarse meal.
Stir in raisins or dried currants, if using, until they're well coated in the flour mixture.
Add the wet ingredients to the dry ingredients and stir together with a wooden spoon until it's so stiff you can't stir anymore.
Tip: It should be a sticky, shaggy dough. But if it's still a bit too wet, add a little more flour.
Turn dough out onto a lightly floured surface, knead just enough to make sure all ingredients are wet, and form into a round shape.
Tip: Do not over-knead this bread or it will get tough. The only purpose of slight kneading for a minute is to make sure all the ingredients are evenly dispersed throughout the dough and get it into a round shape.
Place the dough onto your cast iron pan, dutch oven, baking sheet, or whatever you're going to use to bake it.
Cut a deep X into the top of the bread dough, about 1" to 1-½" deep. This will allow the heat of the oven reach the center of the bread, as well as help the bread expand as it rises.
Bake on the middle rack of the oven for 50 minutes or until a toothpick inserted in the center comes out clean.
Let cool and then enjoy!