Preheat your oven to 350 degrees.

Prepare a 9-inch spring-form pan by buttering the inside edges, and lining the bottom with parchment paper.

Pour the stout into a large saucepan over medium heat. Then add the butter and heat until melted.

Remove from heat.

In a separate bowl, combine the cocoa and sugar, then whisk this mixture into the beer and butter.

In another bowl, combine the sour cream, eggs and vanilla and beat until smooth. Then whisk this mixture into the beer/chocolate mixture until fully combined.

In another bowl (you can use the same bowl that you used for the cocoa/sugar mix, that way you get the remnants of the cocoa left there), combine the flour and baking soda.

Add the flour mix to the chocolate mixture, and combine.

Pour the batter into the cake pan and bake for 50 - 60 minutes, or until a toothpick inserted into the centre comes out clean.

Put the pan on a rack and let it cool completely before removing the cake from the pan.

Garnish with fresh berries, whipped cream, powdered sugar.