Preheat oven to 375°F.
Melt 2 tablespoons butter in a large skillet over medium heat. Add onion and cook until soft, about 5 minutes.
Increase heat to medium-high, and add mushrooms, thyme, soy sauce, and Worcestershire sauce, and ¼ teaspoon of salt. Cook until mushrooms begin to release some liquid, about 5 to 7 minutes.
Add the wine and bring to a boil and cook until reduced, about 2 minutes. Remove from heat and transfer to a bowl. Set aside.
In the same skillet (or a separate saucepan), melt 3 tbsp butter over medium heat, and then whisk in flour, stirring and cooking the roux until light blonde, about 3 to 4 minutes.
Whisk in the milk and then the chicken broth. Stir constantly until thickened, about 4 to 5 minutes. The texture should be thicker than broth, but not as thick a cream gravy.
Stir in the mushroom mixture, lemon juice, 1 tsp salt, and ½ tsp of pepper. Using a fork, flake tuna into the sauce, and gently combine.
Meanwhile, cook the noodles in salted boiling water until al dente, about 7 - 8 minutes. Drain.
Stir in 1 cup of the cheese, all of the peas, and the cooked noodles. Stir gently until fully combined. If using a baking dish, transfer the mixture to the dish.
In a medium bowl, toss together the breadcrumbs with 2 tbsp of melted butter and a pinch of salt.
Add the remaining 1 cup of cheese over the top of the casserole, and then top the cheese with the bread crumbs.
Bake until topping is crisp and sauce is bubbly, about 40 minutes. Let rest for 5 minutes before serving.