Cheesy tuna noodle casserole just like I remember from years ago. But let's make this with our own béchamel sauce with mushrooms and onion. No need for canned soup concentrates.
Cook the noodles according to package instructions, then drain and return them to the pot and set aside.
Preheat your oven to 350°.
Using a 5 to 6 quart Dutch oven or large pot, melt the butter on medium heat then add the sliced mushrooms. Stir them occasionally and cook for 3 minutes. Then add the onion, salt, and pepper and cook for an additional 5 minutes for the onion to become translucent.
Add the all-purpose flour and cook for 1 to 2 minutes stirring to cook off the raw flour taste. Then slowly add the milk while constantly stirring to prevent lumping of the flour. Then stir in the chicken broth. Bring to a boil and cook 3 minutes for the liquid to thicken.
Set your burner to low and add the peas, tuna, and noodles. Toss the noodles to fully coat them with the béchamel. A pasta server spoon works well to mix everything together. Next, add the shredded cheese in small amounts at a time and stir it in to melt and prevent clumping. Remove the pot from the heat and taste and adjust seasonings if necessary.
Coat a 9 by 13-inch casserole dish with cooking spray then pour in the tuna and noodles. Level the casserole with a spoon then apply the potato chips in an even layer. Place the casserole in the oven for 15 to 20 minutes until it browns slightly and bubbles around the edges. Serve hot.
Notes
The tuna that I used was Starkist solid albacore packed in water. 3 cans equaled 12 ounces. Albacore tuna is tightly packed, so I like to use a fork to break it into smaller pieces. This will also prevent the casserole from having "dry" spots that are not very appealing.
You can substitute macaroni pasta for the egg noodles.
Canned salmon or chicken can be used rather than tuna.
Store leftovers refrigerated in an air-tight container for up to 3 days. Reheat in a microwave or in a saucepan on the stove, adding a bit more milk or broth to loosen it up. Freeze for up to 3 months in an air tight container.
If you would like to add some thinly sliced celery, add it in when you add the onion.
Bread crumbs, crumbled Ritz crackers, or Panko bread crumbs can be used rather than potato chips for the topping. Just place them into a small bowl and pour in about a tablespoon of melted butter. Stir the crumbs around to coat with the butter.