Melt butter over medium heat in a medium to large stock pot. Let the butter brown over medium low heat for a couple of minutes, or until golden brown. Whisk in flour and cook over low heat for another 1-2 minutes, whisking frequently to prevent clumping.
Add in chicken broth and stir to combine. Next add in the carrots and zucchini and bring the soup up to a simmer. Simmer for about 15 minutes, or until the vegetables are tender. Blend the soup with a stick blender or traditional blender and return to the pan over low heat. Add the cream, and salt to taste.