Saute onion in olive oil/butter combination. When onions are tender, whisk in flour and cook over med. heat 3-5 minutes stirring constantly.
While whisking, add 1/2 & 1/2 and chicken stock.
Reduce to simmer and cook for 20 minutes, stirring regularly.
Add broccoli and carrots. Cook over low heat until veggies are tender, approx. 45 minutes.
Add salt & pepper to taste.
Carefully transfer soup mixture to blender and puree. Return soup to pot over low heat.
Add in grated cheese. Stir until well blended.
Add nutmeg.