Heat the oil in a pan, then gently cook the shallot and garlic for 5 mins until softened. Transfer to a large bowl. Add the butter beans, then mash together until roughly puréed. Stir in the soured cream, parsley and seasoning. Cover and chill until ready to serve.
Meanwhile, place the slices of bread under a medium grill and gently toast on both sides until light golden. Cut off the crusts and, using a long, sharp knife, split the bread in half, through the centre. Place the bread, untoasted-side up, under a low grill until it curls into a crisp, golden shell. Serve with the butter bean pâté and a sprig of parsley.
Recipe from Good Food Vegetarian Christmas magazine, December 2006