Gooey Chocolate Skillet Cake & Ice Cream Sundae

1 c flour
1/2 tsp baking soda
1 c sugar
dash salt
1/4 c butter
1/4 c vegetable oil
2 TBS cocoa
1/2 c water
1/4 c buttermilk
1 egg
1/2 tsp vanilla

Frosting:

1/4 c butter
2 TBS cocoa
3-4 TBS milk (as needed for consistency)
1/2 c chopped pecans
2 c powdered sugar
1/2 tsp vanilla
ice cream (for serving)
caramel sauce (for serving)
whipped cream (for serving)

Preheat oven to 350.
In large bowl, whisk flour, baking soda, sugar, and salt. Set aside.
In 10-inch cast iron skillet, bring butter, oil, cocoa and water to boil.
Remove from heat and whisk in dry ingredients.
Mix in buttermilk, egg and vanilla.
Bake the skillet cake at 350 for 15-20 minutes.
While cake starts to cool, make frosting.
In medium sauce pan, bring butter, cocoa and milk to boil.
Remove from heat and add powdered sugar, nuts and vanilla. Stir to combine.
Pour over warm cake, spread with spatula.
Serve with ice cream, caramel sauce and whipped cream.