Bring a large pot of water to a boil. Salt the water, add the pasta and cook until al dente.
Place a large, deep skillet over medium heat, add the EVOO, 1 turn of the pan, and melt 1 tablespoon of the butter into the EVOO. Add the onion and celery, cook for 3 minutes, then stir in the bell pepper and cook for 2 minutes. Stir in the flour and cook for 1 minute, then add the wine and reduce for 1 minute. Whisk in the broth and boil for 1 minute to thicken. Reduce the heat to low and stir in the cream; season the sauce to taste with salt and pepper. When it bubbles, add the peas and tuna and cook until heated through. Fold in the tarragon and turn the heat to low.
Preheat the broiler. In a food processor, pulse the bread until coarse bread crumbs form. In a microwavable dish, melt the remaining 3 tablespoons of butter in a microwave and add a little hot sauce. Stir the butter into the bread crumbs to combine.
Drain the shells, toss with the sauce and adjust the seasoning. Place the pasta in a 9-by-13-inch heatproof serving dish and cover with the bread crumbs. Place the dish under the hot broiler and crisp the crumbs for 1 to 2 minutes. Garnish with the parsley.