If you're looking for the best tuna noodle casserole recipe, this is it. It's made totally from scratch - no condensed soup! We're talking a cheesy sauce, loaded with veggies, AND it has a potato chip crumb topping to boot. Just like mom used to make, but better!
Preheat oven to 425 degrees F. Combine the Monterey Jack and cheddar cheeses in a bowl. Pulse the potato chips, bread, ¼ cup cheese mixture, 2 tablespoons butter, ¼ teaspoon salt, and ¼ teaspoon pepper in food processor until coarsely ground, about 8 pulses; set aside.
Place the tuna in a fine-mesh strainer and press dry with paper towels. Transfer to a large bowl and flake into coarse pieces with a fork. Microwave the oil, lemon juice, ½ teaspoon salt, and ½ teaspoon pepper in small bowl for about 30 seconds. Stir the oil mixture into the tuna and set aside.
Bring 4 quarts of water to a boil in a Dutch oven. Add pasta and 1 tablespoon salt and cook until al dente. Drain pasta and rinse with cold water until cool, about 2 minutes. Drain again and set aside. Melt 1 tablespoon butter in now-empty pot over medium-high heat. Add mushrooms and ¼ teaspoon salt and cook until liquid evaporates and mushrooms are browned, 6 to 8 minutes. Transfer mushrooms to the bowl with tuna mixture. Add 1 tablespoon butter, the onion, and bell pepper to now-empty pot and cook, stirring occasionally, until softened, about 5 minutes. Transfer to bowl with tuna-mushroom mixture; set aside.
In now-empty pot, melt remaining 2 tablespoons butter over medium heat. Add flour and cook, whisking constantly, until golden, about 1 minute. Slowly whisk in half-and-half and broth and bring to a boil. Reduce heat to medium-low and simmer until slightly thickened, 5 to 7 minutes. Off heat, whisk in shredded cheese until smooth. Stir in pasta, tuna-vegetable mixture, peas, ½ teaspoon salt, and ½ teaspoon pepper.
Transfer the mixture into a 9x13-inch baking dish and top with bread crumb mixture. Bake until golden brown, 12 to 14 minutes. Let casserole cool on wire rack for 10 minutes before serving. Leftovers can be stored in an airtight container in the refrigerator for up to 3 days.
If you do not have a food processor for the topping, you can do a couple of quick pulses in a blender, or use a pastry blender to combine the bread, butter, salt, pepper and cheeses, then crush the potato chips with your hands and stir in.
If you do not have a microwave, you can warm the olive oil, lemon juice, salt and pepper in a small saucepan over low heat until warmed through, then combine with the tuna.
If you cannot find half and half where you live, simply substitute heavy cream and whole milk in equal parts.
To make this a vegetarian meal, substitute vegetable broth for the chicken broth.
Feel free to substitute other cheeses if you'd like, although I LOVE the combo of Monterey Jack and cheddar!
The casserole can be made ahead. To do so, refrigerate without topping, covered in plastic wrap, for up to 24 hours. Increase the baking time to 25 minutes, adding the topping halfway through baking.
This casserole can also be frozen. Cover tightly in plastic wrap and foil and freeze for up to 3 months. Move from the freezer to the refrigerator 24 to 36 hours before you plan on serving, then follow the baking directions above for a make-ahead preparation.