Preheat the oven to 350°F (175°C).
Cook the whole wheat egg noodles according to package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the chopped onion, celery, and mushrooms. Sauté for about 5 minutes until vegetables are tender.
Add the minced garlic to the skillet and cook for 1 minute until fragrant.
In a large mixing bowl, combine the cooked shredded chicken, sautéed vegetables, thawed peas, cooked noodles, low sodium chicken broth, fat-free Greek yogurt, dried thyme, dried parsley, black pepper, and salt. Stir until all ingredients are well mixed.
Transfer the mixture into a 9×13 inch baking dish and spread evenly.
Sprinkle the grated Parmesan cheese evenly over the top of the casserole.
Bake uncovered in the preheated oven for 25 to 30 minutes, or until the casserole is bubbly and the top is lightly golden.
Remove from oven and let cool for 5 minutes before serving.