# What You'll Need:
→ Pasta and Fish
01 - 12 oz egg noodles
02 - 2 cans (5 oz each) solid white tuna in water, drained
→ Vegetables
03 - 1 cup frozen peas, thawed
04 - 1 cup cremini or white mushrooms, sliced
05 - 1 small yellow onion, finely chopped
06 - 1 cup celery, diced
07 - 2 cloves garlic, minced
→ Sauce
08 - 3 tbsp unsalted butter
09 - 3 tbsp all-purpose flour
10 - 2 cups low-sodium chicken or vegetable broth
11 - 1 cup whole milk
12 - 1/2 cup sour cream
13 - 1/2 tsp kosher salt
14 - 1/2 tsp freshly ground black pepper
15 - 1/2 tsp Dijon mustard
→ Topping
16 - 3/4 cup panko breadcrumbs
17 - 1/2 cup grated Parmesan cheese
18 - 2 tbsp unsalted butter, melted
19 - 2 tbsp chopped fresh parsley (optional)
# How To Make It:
01 - Preheat oven to 400°F. Lightly grease a 9x13-inch baking dish.
02 - Boil egg noodles in salted water until just al dente. Drain and set aside.
03 - Melt 3 tablespoons butter in a large skillet over medium heat. Add onion and celery; sauté for 3 minutes. Add mushrooms and cook an additional 4 minutes until soft. Stir in garlic and cook for 1 minute.
04 - Sprinkle flour over vegetables and stir well to coat. Gradually pour in broth while stirring constantly. Add milk and bring mixture to a simmer, cooking until thickened, about 3 to 4 minutes.
05 - Remove from heat and stir in sour cream, Dijon mustard, salt, and pepper until smooth.
06 - Fold in tuna, peas, and cooked noodles until evenly incorporated.
07 - Pour the mixture into the prepared baking dish, spreading evenly.
08 - Combine panko breadcrumbs, Parmesan cheese, and melted butter. Sprinkle evenly over the casserole.
09 - Bake for 20 to 25 minutes until the topping is golden and the casserole is bubbling.
10 - Allow to rest for 5 minutes. Sprinkle parsley over the top before serving.
