Preheat oven to 400°. On a rimmed baking sheet, place sweet potatoes. Bake until softened, about 1 hour. Remove from oven. Increase oven temperature to broil.
In the work bowl of a food processor, place andouille sausage; pulse until finely ground. In a large bowl, combine sausage, beef, and pork.
Heat a large Dutch oven over medium heat. Add sausage mixture; cook, stirring and breaking up meat with a wooden spoon, until browned. Remove meat using a slotted spoon, and place in a large bowl. Reserve drippings in a small bowl.
Add 1 tablespoon butter to Dutch oven, and melt over medium-high heat. Add ⅓ cup onion, celery, bell pepper, 1 tablespoon Cajun seasoning, Worcestershire, garlic, and hot sauce; cook, stirring and scraping bottom of pan with a wooden spoon, until vegetables are tender, about 5 minutes. Remove onion mixture, and place in a medium bowl.
To Dutch oven, add reserved drippings, carrot, salt, pepper, remaining ½ cup onion, and remaining ½ tablespoon Cajun seasoning; cook over medium heat, stirring frequently, until carrot is tender. Transfer to bowl with onion mixture.
Scoop out sweet potato flesh into a large bowl. Add remaining 1½ tablespoons butter and salt and pepper to taste. With potato masher, mash until smooth. Transfer to a piping bag.
Arrange pastry shells on rimmed baking sheets. To each shell, add 1 heaping tablespoon beef mixture and 1 tablespoon onion mixture. Pipe mashed sweet potato on top, smoothing with a spatula.
Broil until crust is browned, 1 to 2 minutes. Let cool slightly.
Notes
*We used Cajun Maispalm Seasoning (available at cajunculinaryroots.com) and VIP Pastry Shells.
Recipe by Louisiana Cookin' at https://louisianacookin.com/cajun-shepherds-pie/