Bring a large pot of lightly-salted water to a rolling boil.  Stir the pasta into the boiling water.  Cook uncovered, stirring occasionally, until the pasta has cooked through, but is still firm to the bite, about 8 minutes.  Drain well in a colander set in the sink.

Meanwhile, heat the oil in a large saucepan over medium heat.  Stir in the tasso, and cook until golden brown, about 5 minutes.  Stir in the garlic, onion, green pepper, green onion, and celery.  Cook and stir until the onion has softened and turned translucent, about 5 minutes.  Add the basil, thyme, Cajun seasoning, and hot sauce; cook 1 minute.

Pour in the cream, and bring to a simmer over medium-high heat.  Reduce heat to medium-low and stir in the Parmesan cheese.  Cook and stir until the sauce begins to thicken slightly, about 3 minutes.  Add the shrimp and crawfish tails, and cook until hot, then toss with the rotini pasta.  Sprinkle with parsley to serve.