Bring about a gallon of water, with 3 tablespoons of salt, to boil in a large pot.

Add mirlitons and cook covered for 30 minutes, or until tender.

Remove mirlitons to a bowl of ice water to cool.

Once cooled, peel the mirlitons, cut each in half, and remove the seed.

Cut the mirlitons into medium dice and reserve.

Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).

Melt butter over medium heat in a large Dutch oven.

Add onions, bell peppers, celery, bay leaves, salt, pepper, and Creole seasoning to the Dutch oven.

Cook for 25 minutes, until vegetables are soft and the butter browns slightly.

Tear up baguette and grind in a food processor with a metal blade attachment to create breadcrumbs.

Add shrimp to the vegetables in the Dutch oven.

Cook until shrimp begin to turn pink.

Add the ground breadcrumbs to the Dutch oven.

Cook for 5 minutes, stirring constantly, to fully incorporate bread and let it absorb the liquid.

Remove the Dutch oven from heat.

Add the diced mirlitons, sliced sausage, shrimp stock, green onions, and Parmesan cheese to the Dutch oven.

Stir well and adjust seasoning to taste.

Transfer the mixture to a 9-inch-by-12-inch casserole dish.

Top with panko breadcrumbs.

Bake until warm and crusty, about 30 minutes.