Spray a 9-inch cast iron pan or cake pan with baking spray. Set aside.
Add flour, sugar, salt, baking powder, and baking soda to a large bowl. Gently stir until everything is mixed.
Add the softened butter and use a pastry cutter or two knives in a criss-cross fashion to cut the butter into the flour mixture. When butter is sufficiently cut in, the mixture should look crumbly with no big lumps.
Using a wooden spoon, push the flour mixture to the sides of the bowl, leaving a well in the middle. Pour in the buttermilk, sour cream, and whisked egg. Gently fold all the ingredients together until everything is moistened. When only a little dry flour remains visible, stir in the raisins. If the mixture looks too dry and crumbly, add in a little more buttermilk. Be careful not to overwork the dough. You want to stir it as little as possible. The dough should be sticky and look shaggy.
Pour the dough into your prepared baking pan. Sprinkle about one tablespoon (or more) of flour over the top and gently press the dough down so it fills the sides of the pan.
Cut a large cross in the top of the dough. Be sure to cut deeply so that heat can get into the center of the bread.
Bake for 50 minutes. After removing from the oven, let the bread cool for about 10 minutes before removing from the pan.