Step 1

Preheat oven to 375 degrees. Lightly grease a 2 quart baking dish and set aside.

Step 2

Cook noodles according to package directions, removing when al dente. Drain, and set aside.

Step 3

Melt butter in a large skillet over medium heat. Add celery, bell pepper, and onion and cook until onion is translucent, stirring frequently.

Step 4

Stir in flour, salt and pepper.  Slowly add milk and cook, stirring constantly until thick and bubbly. Stir in Dijon mustard.

Step 5

Add tuna, peas, noodles, and cheddar cheese and fold into the sauce.

Step 6

Pour mixture into the prepared dish.

Step 7

Combine Panko, Parmesan cheese, smoked paprika parsley and melted butter in a small bowl and sprinkle over the top.

Step 8

Bake casserole for 25 to 30 minutes, uncovered, or until heated through and golden brown on top. Let stand for a few minutes before serving.