Preheat oven to 375 degrees. Spray a 9x13 baking dish with cooking spray
Cook noodles according to package directions and drain.
While noodles cook, saute mushrooms, onion and garlic. Set aside
In a medium saucepan, melt 1/4 cup butter and whisk in flour, salt and pepper. Add milk, slowly cooking and stirring constantly until sauce is thickened and bubbly.
When sauce is thickened, blend in cream cheese until melted. Combine noodles, sauce, tuna and mushrooms and pour into prepared baking dish.
Combine melted butter and breadcrumbs. Add grated cheese and spread over top of casserole. Sprinkle with smoked paprika.
Bake for 20-25 minutes.