1. Set oven to 400 degrees.
2. Butter a 2-quart casserole dish (use a large dish if you are doubling the recipe).
3. Cook the rice according to package directions; set aside.
4. In a skillet melt butter, add in onion, drained mushrooms and garlic, cook stirring until soft (about 5 minutes).
5. Stir in flour, salt, pepper, half and half cream and broth; cook stirring until thickened (about 5 minutes).
6. Stir in Parmesan cheese, and cook for another 2-3 minutes.
7. Add in cooked chicken, pimiento, parsley, nuts and the cooked rice; mix well with a wooden spoon to combine.
8. Spoon into a casserole dish.
9. Sprinkle with more grated Parmesan cheese.
10. Bake uncovered for about 25-30 minutes.
11. Delicious!