Melt butter in a large saucepan over medium heat. Stir in onion, celery, and carrots and sauté for 5 minutes.
STEP 2
Add mushrooms and sauté for 2 more minutes. Then add flour and stir well. Gradually pour in chicken broth, stirring constantly, until all has been added. Bring just to a boil, reduce heat to low and let simmer.
STEP 3
Add rice, chicken, salt, curry powder, mustard powder, parsley, ground black pepper, almonds, and sherry. Allow to heat through, then pour in the half-and-half. Let simmer for 1 to 2 hours. (Note: Do not boil or your roux will break.)