Heat the oven to 375 F and lightly grease a 2-quart baking dish.

Cook the noodles in boiling salted water following the package directions for al dente. They will cook more in the oven. Drain and rinse with cold water to stop the cooking.

Combine the soup, sour cream, and milk in a bowl; whisk to blend.

Add the tuna, parsley, pimiento, peas, salt, and pepper to the bowl. Stir in the noodles.

Spoon the tuna noodle mixture into the baking dish.

Combine the breadcrumbs and melted butter and sprinkle over the casserole. Sprinkle lightly with paprika if desired.

Bake the casserole for 30 to 35 minutes until the topping is browned and the filling is bubbling.