Let the butter melt in a saucepan, saute the finely chopped onion and let it become light yellow, then add the flour and stir well. Now pour in the bouillon, half of the cream and the chopped ramson and bring to a boil for 10 minutes.Then blend everything in a food processor -not too finely- and season with salt and pepper. Remove from heat, whip the remaining cream and stir it into the soup. Serve with croutons of brown bread.