Cook pasta in a large pot of boiling, well-salted water, until al dente. Drain pasta, reserving 1 cup of pasta water. Toss pasta with olive oil and set aside.
In a large heavy-bottomed pot or saute pan, heat butter over medium-high heat until foaming. Add onion, and cook until translucent (about 8 minutes).
Add garlic and saute another minute.
Add seasoning, cayenne, salt and pepper and continue to cook another couple of minutes.
Add wine and cook until mostly evaporated (1-2 minutes).
Add heavy cream and lemon juice, continuing to cook until slightly reduced.
Add crawfish tails, cooking for one to two minutes before adding green onion, parsley, and ⅓ a cup of reserved pasta water.
Stir until combined then add reserved pasta. Toss to coat, making sure all noodles are well covered.
Remove from heat and stir in ¾ a cup of parmesan cheese and Crystal Hot Sauce.
Serve pasta, and top with reserved parmesan and a little Crystal.