Cook wild rice with olive oil and water according to package directions.
Meanwhile, cook celery, onion, and 1/4 cup almonds in a large skillet with the butter till vegetables are crisp tender and almonds start to brown. (about 5-7 minutes)
Stir in the flour. Whisk in milk and chicken broth. Cook and stir till mixture comes to a boil. Boil and stir for at least one minute.
Add pepper, salt, parsley, cooked chicken, and prepared wild rice mix. Stir to combine and pour into a greased casserole dish.
Top with remaining 1/4 cup slivered almonds. Bake uncovered at 400° for about 20-25 minutes or till hot and bubbly.