Sweat the onion in butter and add the chanterelles (chanterelles). Let simmer while stirring until there is no more liquid. Season with salt and pepper, leave to cool. Stir butter with herb salt until foamy, stir in goat or sheep cheese. Mix in the chopped parsley, chives and the chanterelles. Pour the mixture into a terrine dish lined with cling film and chill. Fall out of shape. Cut into slices with a hot, damp knife, serve.