To begin, cook the egg noodles al dente according to package directions.
Preheat your oven to 375 degrees.
Meanwhile, finely dice your onion.
Sauté it in a skillet with a tablespoon of the butter. Cook these over medium heat until the onions are tender.
Add in the sliced mushrooms. Let those cook for 2 minutes.
Add in two tablespoons of cognac and let that cook for a minute. Turn off the heat.
In a saucepan, melt 3 tablespoons of the butter. Add in the flour and whisk it smooth. Let it cook for just a minute and let it get bubbly. Whisk in the milk and chicken broth. Add in the black pepper, salt, and soy sauce. Stirring continually, bring this to a gently boil and let it thicken. After it has boiled for one minute, turn off the heat.
Add in your mushroom & onion mixture. Stir it together.
In a mixing bowl, combine the cooked noodles and sauce. Add in the tuna and frozen peas. Stir these all together and spread it into a greased, 2-quart casserole dish.
In a bowl, combine the panko bread crumbs, shredded cheddar cheese, and remaining 1 tablespoon of butter, melted. Stir it until the butter is incorporated throughout the crumbs. Spread the mixture over the top of the casserole.
Bake for 30 minutes or until the crumb topping is golden brown. Enjoy!