Pumpkin and Orange Soup

A creamy soup with lots of flavour and beautiful colour.   Ingredients 1 small pumpkin, peeled and seeded 1 leek, sliced 4-5 small carrots, peeled and chopped 1 onion, peeled and chopped 1 large potato, peeled and chopped 1 tsp dried rosemary Finely grated zest and juice of 2 oranges crème fraiche ( optional) 1