Preheat oven to 350°F. Generously grease a 10-inch cast iron skillet with butter or non-stick spray.

Make the chocolate base: In a saucepan, bring the water, 4 tbsp cocoa powder, and 8 oz butter to a boil over medium heat. Remove from heat and set aside.

In a large bowl, whisk together the 2 cups flour, 2 cups sugar, 1 tsp baking soda, and 1/2 tsp salt.

In a small bowl, lightly beat the 2 eggs. Whisk in the 1/2 cup sour cream and 1 tsp vanilla.

Pour the egg mixture into the dry ingredients and stir just until combined.

Fold in the warm chocolate base until you have a smooth, chocolatey batter.

Pour batter into prepared skillet and spread evenly.

Bake for 30-35 minutes until edges are set but center still jiggles slightly.

Make the frosting: In a saucepan, bring the 6 tbsp milk, 3 tbsp cocoa powder, and 4 oz butter to a boil.

Remove from heat and whisk in the 3 3/4 cups powdered sugar until smooth and pourable.

Gently stir in the 3/4 cup pecan pieces.

Pour warm frosting over warm cake and spread to edges.

Allow to cool 10-15 minutes before serving warm, scooping out gooey cake portions.