Bring large pot of cold water to boil. Season with plenty of salt and throw in pasta shells. Cook until almost done. It’s better if they’re slightly under-cooked, as they’ll continue to cook while baking. Drain, rinse with cold water and set aside.
Set large skillet over medium-high heat. Add 2 tablespoons butter and once melted, throw in sausage. Cook until browned and crispy on all sides, about 4 to 5 minutes.
Using slotted spoon, transfer sausage to plate or platter, leaving the drippings in the skillet. Add chicken to hot skillet and cook until browned as well, about 5 to 6 minutes. Transfer to the plate with sausage.
Add remaining 2 tablespoons of butter to skillet and add veggies, bay leaves and thyme. Cook until softened, about 8 minutes. Season with creole seasoning, salt and pepper. Remove from heat and let cool slightly.
In large bowl, combine ricotta cheese with 3/4 cup mozzarella cheese. Add cooled veggie and meat mixture and stir until well combined.
For the Creole Cream Sauce:
Set medium saucepan over medium-high heat and add butter. Once melted, whisk in flour and cook for about 30 seconds. Slowly add half and half and milk while continuously whisking. Lower heat and cook until sauce has thickened. Season with Creole seasoning and hot sauce.
Preheat oven to 350°F.
Pour about a cup of sauce into 9 by 13-inch baking dish and spread it out in an even layer. Fill each pasta shell with about a tablespoon or so of filling and place in baking dish. Continue filling all shells and placing them snugly into baking dish. Pour remaining sauce on top of shells and sprinkle with remaining mozzarella cheese. Bake until bubbly and melted, about 15 to 20 minutes. Place under broiler (keeping an eye on it) for the last 5 minutes of cooking to brown top. Remove from oven and garnish with scallions. Enjoy immediately!