Heat the butter, stir in the flour and sweat until light. Deglaze with cream, milk and stock, stirring constantly, stir until smooth and simmer for about 10 minutes, stirring frequently, so that the flour taste disappears. Peel the banana and finely mash it with a fork. Season the soup with the spices and stir in the banana. Cut the ham into fine strips and add to the soup with the shrimp.