Preheat the oven to 350 degrees F.
Bring a pot of water to boil and cook the egg noodles according to package directions.
Meanwhile, make the rest of the casserole.
Heat a large saucepan over medium heat.
Add the olive oil and butter.
Once the butter is melted, add the onions and mushrooms, season with salt and garlic powder, and cook until softened, about 8-10 minutes.
Add the flour to the mushrooms and onions and mix to combine, cooking another minute.
Slowly stir in the milk followed by the chicken broth.
Cook another 3-4 minutes, until the sauce has thickened.
Combine the sauce with the cooked noodles, tuna, and 1 cup of the shredded cheddar cheese.
Pour the mixture into a greased 9x13” pan and then top with the remaining cheddar cheese and crushed potato chips.
Bake in the preheated oven for 20 minutes, until bubbling and golden brown.
Serve immediately topped with fresh chopped parsley.
Enjoy!