Preheat oven to 475 F.
Sift the self-rising flour, cake flour, baking powder, baking soda, sugar and salt into a large bowl. Using your fingers or a pastry cutter, work the 4 tablespoons cold butter into the flour until the pieces are pea size.
Add the bacon, cheddar and green onions to the flour mixture. Pour the heavy cream into the flour mixture and, with your hands or a silicone spatula, stir just until the cream and flour come together to form a dough.
Use 2 tablespoons of the melted butter to brush the inside of the Cast-Iron Biscuit Pan.
Carefully spoon mixture into each well being sure to divide the mixture evenly between all wells. This will ensure even baking. Gently smooth each top with the back of a spoon or spatula. Brush the tops with the remaining tablespoon of melted butter.
Bake in the oven for 10 or 12 minutes, or until golden brown. Allow to cool briefly before running a thin, sharp, small blade around the edge of the biscuit pan and inverting the pan to release the biscuits.