In a saucepan on low heat melt butter with beer. Remove and cool slightly.

Whisk in sugar, espresso, cocoa.

In a separate bowl whisk sour cream, vanilla, eggs then combine with beer mix and whisk. Sift in flour and B.Soda and fold into mixture gently.

Put into non-stick muffin tray, or paper cases 3/4 full.

Bake mod oven approx 170C - 25mins depends on your oven .