Preheat the oven to 450°F. 

Set a 10-inch cast-iron skillet over medium heat and add the bacon to it.  Render the bacon, stirring often until the fat has rendered out, and the meat is caramelized, about 5-6 minutes.  Use a slotted spoon to remove the bacon from the pan and set aside.  Remove the pan with the bacon fat in it from the stove and place in the oven.  Turn off the fire on the stove.

While the pan heats up in the oven, in a medium-sized bowl, combine the cornmeal, baking powder, baking soda, salt, pepper, cheddar cheese, green onions and the rendered bacon and mix well.  In a small bowl combine the buttermilk, egg and melted butter.  Add to dry ingredients and stir just to combine.

Remove the hot skillet from the oven, carefully swirl to evenly distribute hot grease, and quickly pour the cornmeal batter into the skillet.  Bake for 25 to 30 minutes, or until firm and golden brown on top.  Let sit for 5 minutes, then turn out onto a cutting board.  Cut into wedges and serve hot with butter on the side.