CARROT & ORANGE SOUP

¼ cp unsalted butter
2 ½ cps chopped yellow onions
12 large carrots, peeled and chopped
5 cps chicken or vegetable broth
1 cp fresh orange juice 
salt and pepper to taste
grated zest of orange
1/8 tsp cinnamon 

Heat butter in large saucepan. Cook onions in the butter over low heat for 25 minutes or until tender, stirring occasionally. Add carrots, broth to onion mixture, mix well. cook until carrots are tender, stirring occasionally.
Reserve 1 cp of the broth.
Remove solids to a blender using a slotted spoon. Add a small amount of the mixture and process until puréed. Return to the saucepan mix well. Stir in orange juice and reserved broth. stir in the orange zest. Simmer just until heated.