Adapted from [Willow Bird Baking|http://willowbirdbaking.com/2012/04/25/gooey-chocolate-skillet-cake-ice-cream-sundae/]
Yields: 4-6 servings
Preheat oven to 350. In a mixing bowl, stir together the flour, baking soda, sugar, and salt. Set aside.
Place a 12-inch cast iron skillet over medium heat. Melt the butter. Whisk in the oil, cocoa powder, and water and bring it to a simmer. Remove it from the heat and mix in the dry ingredients until well combined. Whisk in the buttermilk, egg, and vanilla until smooth. Place the skillet in the oven and bake 15-20 minutes or until just set.
As soon as the cake is out of the oven, begin making the frosting. In a saucepan over medium heat, whisk together the butter, cocoa, and milk and bring to a simmer. Remove from heat and whisk in the powdered sugar, pecans, and vanilla. Pour the warm frosting over the warm cake and spread gently with a spatula to cover.
Serve warm with vanilla ice cream.