Pre-heat oven to 350° F.
Grease your cast iron skillet or your 9 inch cake pan.
In a medium mixing bowl, whisk together the sugar, flour, baking powder, baking soda, and salt until combined. Add your raisins to your dry mix and using a rubber spatula, stir to combine.
In a separate smaller bowl, whisk together your eggs, buttermilk and sour cream until everything is combined.
Pour your wet mixture into your dry mixture and, using a rubber spatula, stir until everything is incorporated. Make sure to scrape the bottom and sides of your bowl.
Using a folding motion, keep moving your dough around for about 30 seconds. Your dough should start to come away from the sides of the bowl (it should still be super sticky). Once it starts coming away from the sides, it is ready to put into your cast iron skillet or a 9 in cake pan.
Once your dough is in the pan, cut an X into the top of the bread. If your dough is still really sticky and hard to cut, run your knife under water before you score your bread.
Using a pastry brush, brush the top of your bread with some buttermilk.
Bake for 55-65 minutes until golden brown, and if you poke in the center with a toothpick, the toothpick comes out clean.