Prepare the Pasta

1. Cook bow tie pasta according to package directions
2. Drain and keep warm

Make the Roux

1. Melt butter in a large Dutch oven or heavy-bottomed pot over medium heat
2. Add flour and cook, stirring constantly, until smooth and lightly blended, about 2 minutes

Cook the Vegetables

1. Add green onions, onion, garlic, bell pepper, and celery to the roux
2. Sauté until vegetables are tender, about 5 minutes

Build the Sauce

1. Stir in the chicken base.
2. Stir in heavy cream, crawfish tails, diced tomatoes with green chilies, Cajun seasoning, parsley, pepper, and salt
3. Simmer, stirring occasionally, until the sauce thickens, about 10 minutes
4. Add hot sauce if desired

Serve

1. Spoon sauce over warm pasta
2. Top with shredded Parmesan cheese
3. Garnish with additional chopped parsley if desired