• Preheat the oven to 350°F and grease an 18x13 inch baking pan.
• Melt the butter over medium heat in a saucepan.
• Whisk in the cocoa powder until well combined. Allow the mixture to cool slightly.
• Mix the flour, granulated sugar, and baking soda in a bowl.
• Slowly add the cooled butter and cocoa mixture to the dry ingredients, stirring until well combined.
• Mix in the sour cream and eggs to the batter until smooth.
• Transfer the batter to the prepared baking pan and spread it into a smooth, even layer.
• Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean.

Frosting

• While the cake is baking, make the frosting by melting the butter in a saucepan.
• Stir in the cocoa powder and milk.
• Remove from the heat and allow it to cool slightly.
• Whisk in the confectioner’s sugar until smooth.

Decorate

• Once the cake is baked and slightly cooled, pour the frosting over the warm cake and spread evenly with a spatula.
• Sprinkle the top with the chopped pecans for decoration.
• Allow the cake to cool completely before slicing and serving.