Preheat oven to 350°
Add the butter, orange juice, 3/4 cup brown sugar, and ground ginger to the cast iron skillet.
Place the pan in the oven while you make the cake batter.
If you are using a 10-inch spring form pan you will have to do the caramel sauce on the stove top.Pour the melted butter into a small saucepan. Add the brown sugar, dried ginger, and orange juice. Cook, stirring, under low-medium heat until the mixture is smooth. Pour the mixture into the prepared pan. Cream the butter and sugars together for several minutes until they are light and fluffy.
Add the eggs, one at a time, mixing to combine. Then add the sour cream, and vanilla, also mixing to combine.
Add the ginger and zest and mix to combine.
Add the flour and buttermilk in batches starting with the flour and ending with the flour.
Remove the cast iron pan from the oven and starting at the center of the pan, place a half of a fig, cut side down. Place more halves around that one (also cut-side down), and a second circle. Try to place the halves close together so they won't move, but do not overlap them. Set the pan aside
Using a spoon or spatula, add dollops of the batter to the pan with the topping, making sure not to move the figs or mix the topping and the cake batter. Gently smooth the batter on the top so that it is even.
Bake for 45-55 minutes until a toothpick or cake tester comes out clean. Let the cake rest on a cake rack undisturbed for 15 minutes. Then slide a sharp knife around the edge and place a platter on top of the cake. Quickly and firmly turn the cake upside down. If it does not release, or you think it hasn't, gently rap on the pan then pull it up and off the cake.
Let the cake cool before cutting. Serve alone or with whipped cream or ice cream.