Melt the butter in a large saucepan. Add the onion, broccoli, carrots and half of the broth. Cover and cook on medium heat for about 10-12 minutes, until vegetables are soft. Whisk in the flour.
Whisk in the milk, onion powder, oregano, salt and pepper. Stir the remaining vegetables. Add in the remaining broth.
Allow to simmer for 15-20 minutes. Stir in the cheese right before serving, heating until melted.