There’s lots of yummy toppings you can use: Panko bread crumbs, crushed potato chips, crushed crackers or crispy fried onions. You can prepare this casserole in advance. But when baking the next day, add extra time because the whole casserole is cold. For the tuna, we found a big flavor and texture difference by using the solid white chunk albacore tuna vs the chunk light style tunas. Feel free to use more or less tuna depending on your personal taste preference.
Preheat oven to 400°F. Lightly oil or butter a 9x13 pan.
Cook the pasta: Cook egg noodles according to package instructions. Drain and pour into the prepared 9x13 pan.
Make the crumb topping: In bowl combine bread crumbs, melted butter and parmesan cheese. set aside.
Make the filling: Heat large skillet on medium-high heat. Add oil and cook onions and celery until softened. Add peas/carrots, garlic and chicken broth. Stir and bring mixture to a simmer.
Whisk flour into the milk, then add the whisked mixture into the simmering pan with the veggies and broth. Stirring regularly, cook until mixture thickens, then add tuna, salt and pepper. Remove from heat and taste the mixture. Add more salt/pepper if needed.
Pour the tuna mixture into the pasta pan and stir in the cheese. Top the pan with the bread crumb mixture.
Bake for about 20-25 minutes or until bubbly and crispy brown. Serve warm.