Melt the 1/4 cup butter and sautee the 1/2 medium chopped onion in the butter until soft. Sprinkle the 1/4 cup flour over the mixture. Cook and stir over medium heat for 1-2 minutes.
Whisk in the 2 cups half-and-half cream and 2 cups low-sodium chicken stock or broth. Bring to a boil then reduce heat to medium.
Add the 1/2 lb broccoli and 1 cup carrot. Cook over medium-low heat for 20-25 minutes or until the broccoli and carrots are tender.
Add salt and pepper. You can leave the soup chunky or blend about 1 cup of the soup and stir it in for a smoother soup (that's what I do). Return to low heat and add the 8 ounces grated sharp cheddar cheese. If your heat is too high your soup can get grainy. Stir in the nutmeg if desired.