Preheat oven to 350°F.
Butter or spray a bundt pan well; (Some people even go so far as to brush the inside of their bundt pans with melted butter–you cannot be too careful!).
In a heavy large saucepan over medium heat, bring the stout and butter to simmer.
Add cocoa powder and whisk until the mixture is smooth.
Whisk flour, sugar, baking soda, and teaspoon salt in a large bowl to blend.
Using an electric mixer or a whisk, beat eggs and sour cream in another large bowl to blend.
Combine stout-chocolate and egg sour cream mixture
Add flour mixture and beat briefly on slow speed or use a whisk.
Mix batter lightly until completely combined.
Pour batter into prepared pan.
Bake cake for about 35 minutes or until a skewer or other tester inserted into the center comes out clean. Cool cake, cover with ganache or garnish with other treasures and add ganache on individual plates.