• Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with nonstick cooking spray and set aside.
• Bring a large pot of salted water to a boil over high heat. Add the egg noodles and cook for 2 minutes less than the package directions, which will be about 4 to 5 mins. If the package lists an al dente cook time, use that or a minute less.

  Mom's Tip: The noodles should still feel slightly firm when you bite into one, since they will finish cooking in the oven. Drain well in a colander and set aside.
  12 oz wide egg noodles
• While the noodles cook, melt the butter in a skillet over medium heat. Add the diced celery and onion and cook, stirring occasionally, until the vegetables are soft and the onion is starting to look translucent around the edges, about 5 to 7 minutes. Remove the skillet from the heat.
  2 tablespoon salted butter, 1 large stalk celery, ½ medium yellow onion
  
• While the noodles and veggies cook, combine the cream of mushroom soup, sour cream, milk, onion powder, garlic powder, and salt in a large mixing bowl until smooth with no lumps. Add the drained tuna and break it up gently as you stir. You want some chunks to remain so the tuna stands out in every bite.
  2 (10.5 oz) condensed cream of mushroom soup, 1 cup sour cream, 1 cup whole milk, 1 teaspoon onion powder, ½ teaspoon garlic powder, ½ teaspoon kosher salt, 2 (5 oz) cans solid white albacore tuna packed in water
• Stir in the cooked celery and onion, the frozen peas, and 1 ½ cups of the shredded cheddar. Add the drained noodles and fold everything together gently until all the noodles are coated.
  1 cup frozen peas
  
• The casserole mixture will be thick and creamy and will thicken more as it bakes.

  Mom's Tip: If the tuna noodle casserole mixture looks TOO thick before baking, stir in an extra 2 to 3 tablespoon of milk. The sauce should look creamy and loose enough to shift when you tilt the bowl. It will thicken as it bakes. If it looks thick and paste-like going in, it may bake up too dense.
• Pour the noodle mixture into the prepared baking dish and spread into an even layer. Scatter the remaining ½ cup of shredded cheddar evenly over the top.
  
• In a small bowl, stir together the crushed crackers and melted butter until the crumbs are evenly coated. Spread the topping in an even layer over the cheese, covering the casserole from edge to edge.
  1 sleeve buttery round crackers, 3 tablespoon salted butter
  
• Bake uncovered for 25 to 30 minutes, until the edges are bubbling and the cracker topping is deep golden brown. If the top browns too quickly before the edges bubble, loosely tent the dish with foil for the last few minutes.
  
• Let the casserole rest for 5 minutes before serving so the sauce can settle and thicken slightly.
  

Freezing

• If you are making this ahead for meal prep and want to freeze, it works beautifully! The best option is to prep it and freeze before baking.
• Assemble through the cheese layer (no cracker topping), wrap tightly in plastic and foil, freeze for up to 2 months.

  Thaw frozen casserole overnight in the refrigerator. Add the fresh cracker topping and bake as directed, adding 10-15 extra minutes since the dish is cold in the center