Preheat the oven to 350°F (180°C). Spray a 9×13 inch baking dish with non-stick baking spray. In a large bowl, combine the dry ingredients: flour, sugar, baking soda, baking powder, and salt until well combined. Set aside.
In a medium saucepan, over medium heat combine a can of Coca-Cola with cocoa powder, butter, and salt. Let the butter melt completely, then bring to a boil and remove from heat. Allow it to cool for a few minutes.
After the Coca-Cola mixture has cooled, pour it into the dry ingredients and whisk until combined. Add the eggs, sour cream, and vanilla extract. Mix well using a whisk until all ingredients are well incorporated.