Step 1

Preheat the oven to 350 degrees F. Grease a 10-inch cast iron skillet with softened butter.

Step 2

In a small saucepan over medium heat, bring to a boil the water, butter and cocoa powder, stirring frequently. Remove from heat.

Step 3

In a large bowl, stir together the flour, sugar, baking soda and salt. Stir in the egg, sour cream and vanilla. Pour the chocolate mixture into the flour mixture and stir until combined and smooth.

Step 4

Pour the batter into the prepared skillet. Bake in the preheated oven for 25 to 35 minutes or until a tester inserted into the center comes out clean.

Step 5

Remove the skillet from the oven and place on a wire rack.

Step 6

Just before the cake is finished baking, combine the milk, cocoa powder and butter in a small saucepan over medium-heat; bring to a boil, stirring frequently. Remove from heat. Whisk in the powdered sugar until smooth. When the cake is done and still hot from the oven, pour the icing over the cake. Using the back of a spoon, spread it evenly. Sprinkle the toasted pecans evenly over the icing.