Preheat oven to 350 degrees.
Cook your pasta of choice according to package directions. Drain and set aside.
Prepare a 13 x 9 pan with cooking spray. Set aside.
Drain cans of tuna or salmon, remove any noticeable large bones and flake with a fork. Set aside.
In a large skillet melt ¼ cup of the butter over medium heat.
Add mushrooms, celery and onions.
Sauté until tender, stirring regularly; about 5 minutes.
Add peppers and garlic.
Stir for another minute.
Sprinkle flour on top of vegetables and stir until flour is golden; between 3-4 minutes.
Gradually add milk or cream and stir.
Add Worcestershire sauce, stirring constantly until it thickens.
Add cheddar cheese and stir until melted.
If using milk, add sour cream. If using heavy cream, do not add sour cream.
Add salmon or tuna and pasta. Stir until combined.
Using a spatula, dump mixture into your prepared pan.
If using potato chips, no need to melt butter. Sprinkle crushed and broken chips on top of your casserole and add another cup of cheese (if desired). In my opinion, the potato chips taste better with a little more cheese sprinkled in .
Melt remaining butter in a small saucepan over medium heat and add crumbs, cereal or crackers.
Remove saucepan from heat and using a fork to coat crumbs or crackers with butter.
Sprinkle crumb mixture over top of the casserole.
Bake until top is golden and casserole is bubby; about 30 minutes.
Let stand approximately 10 minutes before serving. Enjoy!