Prepare all of the ingredients. Preheat oven to 400deg. Start boiling water for shells
Add pasta to boiling water. Cook as directed by package. Drain in a colander and rinse with cold water to arrest cooking process. Set aside.
In a large saute pan over medium high heat, add oil, onions and garlic. Cook for 3 minutes then add ground beef, salt, pepper, and paprika. Cook for until mostly no pink then add green bell peppers. Cook another 4 minutes then drain excess liquid and set pan aside.
In a saucepan over medium heat, add butter, garlic powder and salt. Once melted, whisk in flour and let cook for 3 minutes. Whisk in chicken broth and cook another 2 minutes. Whisk in heavy cream and cook another 2 minutes. Finally whisk in cheese and cook another 3 minutes.
Pour half of cheese sauce into meat mixture and stir to coat evenly.
In a 13 x 9 glass baking dish, pour a thin layer of cheese sauce in bottom and then line up jumbo shells in rows. Fill each shell with a portion of meat and cheese mixture. Pour remaining sauce over top. Then cover with provolone cheese slices, sharp cheddar and parsley. Place in oven for 20 minutes.
Serve 4-6 shells per person and top with Scallions.