Cook tortellini and egg noodles according to package directions until al dente, drain, and set aside. (I prefer to add both to the same pot, and adjust when I add the tortellini to the pot based on the cooking times of each pasta.)
Grease a 9”x12” glass or ceramic baking dish with cooking spray or butter and set aside. Set your oven racks in the top and middle, and preheat your oven to 350 degrees.
In a large, deep sauté pan, melt 2 tablespoon butter over medium-low heat, and season celery and onion. Season with salt and pepper, and cook until soft and slightly translucent, about 5 minutes, stirring occasionally.
Add celery seed, onion powder, garlic powder and cook 1 minute.
Gradually stir flour into veggies/butter until well combined. Cook, stirring frequently for 1-2 minutes.
Using a wooden spoon or whisk, gradually stir half and half and cream into flour mixture, and continue to stir until completely combined. Cook 6-10 minutes, stirring occasionally, until sauce begins to thicken. Once slightly thickened, add the fresh dill, frozen peas, nutmeg, dijon mustard, and half the cheddar (reserve the rest for topping casserole), and stir to combine.
Remove sauce from heat, and add cooked noodles/tortellini and drained tuna directly to the pan with the sauce. Toss to combine until all noodles are well coated.
Transfer noodle/sauce mixture to your greased baking dish, and sprinkle reserved shredded cheddar in an even layer, followed by the crushed kettle chips. Cover with foil, and transfer the baking dish to the oven.
Bake on middle rack covered for 30 minutes, then uncovered on top rack for 15 minutes.