Spray a 9x13 baking dish with nonstick cooking spray.
ook long grain and wild rice mix according to package directions-takes 5 minutes. Combine this and the cooked white rice in a large bowl; set aside while making sauce.
In a large skillet, melt butter. Add onion and celery and cook on medium high heat, stirring, just until onion is translucent, 1-2 minutes. Add cream cheese; reduce heat to medium and stir until melted. Remove from heat.
To the rice in bowl, add water chestnuts, cream cheese mixture, 1 t. salt, ½ t. black pepper, milk, soy sauce and 1 c. of the shredded cheese. Stir thoroughly and pour into prepared pan.
Sprinkle with remaining 1 c. shredded cheese and bake 20-25 minutes, or until hot and bubbly.