1. Preheat oven to 375°.
2. Cook pasta according to package directions, omitting salt and fat; drain.
3. Melt butter in a medium saucepan over medium heat. Stir in flour; cook 2 minutes, stirring constantly with a whisk. Gradually add stock and milk; bring to a boil. Reduce heat, and simmer 5 minutes. Remove from heat; stir in 2 ounces Parmigiano-Reggiano cheese, cream cheese, salt, and pepper.
4. Heat a large skillet over medium-high heat. Add 1 tablespoon oil to pan; swirl to coat. Add mushrooms; sauté 3 minutes, stirring occasionally. Add onion, garlic, and thyme; sauté 3 minutes. Add wine; cook 1 minute. Combine milk mixture, mushroom mixture, pasta, chicken, and peas; toss to combine. Spoon the pasta mixture into a 13 x 9-inch glass or ceramic baking dish coated with cooking spray.
5. Place bread in a food processor; drizzle with 1 teaspoon oil. Process until coarse crumbs form. Combine breadcrumbs and remaining Parmigiano-Reggiano; sprinkle evenly over pasta. Bake at 375° for 30 minutes or until browned and bubbly. Top with parsley.