2 cups chopped celery, divided
2 cups chopped carrots, divided
4 tablespoons butter
2 cups onions, diced
3 tablespoons flour
6 cups hot vegetable broth, divided
Salt and pepper to taste
1 cup heavy cream

In a small saucepan add 1 cup celery, 1 cup carrots, 1 cup vegetable broth.
Bring to a boil and cook until tender, about 4 minutes. Drain and reserve cooked vegetables.
In a large saucepan, over medium high heat, melt butter. Add onions and saute until clear.
 Whisking, add flour, cook 2 minutes making sure flour does not brown.
Add 5 cups vegetable broth and continue to whisk until mixture boils, making sure to reach the bottom of the pan.
Add uncooked 1 cup celery and 1 cup carrots. Bring mixture to a boil, reduce heat, and simmer about 30 minutes.
When cooked strain soup through a fine sieve into a clean pot reserving vegetables.
In a blender puree vegetables with 1 1/2 cups of liquid. Stir puree into pot with liquid. Stir in cream, reserved vegetables.
Heat and serve.