Cook noodles according to package directions.
In a large skillet, heat olive oil over medium heat. Add onions, zucchini and celery. Sauté until tender (about 7-10 minutes).
In a large bowl combine tuna, sour cream, mayonnaise, Dijon mustard, garlic powder, thyme, basil and black pepper.
Add vegetable mix and cooked noodles to the large bowl and stir until combined.
Place noodle mixture into a 2 1/2 quart casserole dish.
Cover and bake at 375 degrees Fahrenheit for 30 minutes. Uncover, add cheese and cook for another 5-10 minutes until cheese is melted.