Brown sausage in a large skillet. Remove to a bowl and set aside.
Add 4 tablespoons butter to the skillet and cook celery, red pepper, and onion until soft.
Add garlic and cook 1 minute.
Add crawfish, 2 teaspoons Tony Chachere's and black pepper. Mix together and remove from heat.
In a large bowl, whisk together eggs, half-and-half and remaining 1 teaspoon Tony Chachere's seasoning. Add cornbread stuffing, parsley, and crawfish mixture. Mix together well.
Add enough chicken broth to moisten the mixture.
Transfer to a greased 9x13-inch pan. Scatter butter slices on top. Cover with aluminum foil and bake 40 minutes at 350 degrees. Uncover and bake 15 more minutes.