Preheat the oven to 350°F. Spray a 13 x 9 inch baking dish with cooking spray. Set aside.
Cook noodles per the package in salted water until al dente. Drain well.
Meanwhile in a deep large saucepan, cook together butter, celery and onion for 2 minutes over medium until softened. Add flour, stirring until absorbed to make a roux. Simmer 1 minute.
To the roux add salt, lemon pepper, seafood seasoning, garlic and onion powders. Mix well.
Increase heat to medium-high and gradually mix in milk. Stir until fully combined, bring to a boil. Immediately lower heat and allow to gently bubble for 5 minutes. Remove from heat, mix in 2 cups cheese until melted.
To the pot add noodles, tuna and peas. Mix well, and pour into baking dish. Sprinkle with remaining 1 cup cheese and fried onions.
Bake for 30-35 minutes or until golden and bubbly. Serve immediately garnished with fresh chives or parsley, if desired.