- Add butter to small saucepan. Sauté onion until soft. Set aside.
- Add butter to stockpot. Melt over medium heat. Whisk 3-5 minutes.
- Whisking continuously, slowly add in the half-and-half. Stir in chicken stock and continue whisking.
- Reduce heat to low. Stir in broccoli, carrots, and onion. Simmer 20 minutes.
- Season with salt and pepper.
- Add soup in batches to blender. Pureé until smooth.
- Return to stockpot. Reduce heat to low. Stir in grated cheese.
- Stir in the nutmeg. Serve hot.