Place 1 to 2 T. bacon grease in skillet and then place skillet in the oven. Preheat oven to 450 degrees with skillet inside.
Add all-purpose flour, baking powder, baking soda and salt to mixing bowl. Whisk to together well. Grate cold butter into the flour mixture and incorporate with a fork, fluffing and coating butter with flour as you go. Create a well in the middle of the flour mixture and pour in buttermilk. Mix well with fork until the dough reaches a shaggy consistency. DO NOT overman. Set aside until the oven has reached it's temperature.
Once the oven has reached 450 degrees, CAREFULLY remove the skillet and pour the Skillet Bread dough into the pan. Spread and even out as well as you can but don't sweat it. Rustic is good! Return to the oven.
Bake for 10 minutes and remove from oven. Use a large spatula and quickly flip the bread in the skillet. If the bread is not yet firm enough to flip, return to the oven and bake for an additional 5 minutes before trying to flip the bread again.
Once the Skillet Bread has been flipped, return to the oven for an additional 10 to 15 minutes.