Preheat grill to 350 degrees F. Generously coat a Bundt pan with nonstick spray.

Bring stout and butter to a simmer in a saucepan over medium heat. Add cocoa powder and whisk until mixture is smooth. Cool slightly.

In a medium bowl, whisk together flour, sugar, baking soda, and salt. Using an electric mixer, beat in eggs and sour cream until blended. Add stout-chocolate mixture and beat to just combined. Then, on slow speed, add flour mixture. Using a rubber spatula, fold the batter until completely combined. Pour batter into Bundt pan and place on indirect heat on the grill for 45 minutes. A toothpick should come out clean when done. Remove cake from grill, and place on wire rack to cool for 10 minutes. Then turn cake out onto rack to cool completely.

Serve with your favorite stout and some whipped cream.