Cook pasta according to the instructions on the box. Set aside. Reserve ¼ cup of the pasta boiling liquid.
Peel, devein and rinse the shrimp, pat dry with paper towels and mix in 1 Tablespoon of creole seasoning-then set aside in a bowl.
Slice sausage into medalions, chop shallots, garlic and green onions. Measue butter, stock, heavy cream, lemon juice and creole seasoning. Set aside.
To begin, sauté the sausage in the olive oil over medium high heat for about 5 minutes. Remove the sausage from the pan and set aside.
Add the shrimp to the frying pan and saute for about 2 ½ minutes, total. Turn the shrimp over once to make sure you catch both sides. Remove the shrimp from the pan and set aside. Leave the oil and browned bits of sausage and seasoning in the pan.
Next add the butter.When the butter is just melted and starting to bubble, add the shallots and sauté for about 3 minutes.
Add the the garlic and stir until just aromatic - a minute or two. Add about half the creole seasoning, mix well.
Deglaze the pan with a little chicken stock, scraping all the browned bits off the bottom. Add the remaining chicken stock and mix well.
Add the lemon juice. Mix everything together well and bring to a low boil before lowering the heat. Simmer with the pan uncovered for about 5 to 8 minutes, until the stock has reduced by about half.
Add in the heavy cream and mix well. Increase the fire and bring everything to a boil, then lower the heat to maintain slight simmer. Stir in the green onions. Keep it at a simmer for about 5 minutes then stir in the creole mustard and mix well.
Add back the sausage and stir to combined completely.Simmer about 2 to 3 minutes,
Add back the shrimp and the remaining creole seasoning and salt and pepper. Mix well, cover the pan and simmer about 3 minutes.
Now is the time to add in the cooked pasta. Start with about half of the pasta and ¼ cup of pasta water and mix thoroughly. Add more as you mix it together but don't add so much that the sauce doesn't coat all the pasta. You may not use all of the pasta as it should be creamy and all the pasta should be coated with the sauce.
Remove from the heat and let sit about 5 minutes then serve.