Cut seafood into bite-sized pieces and refrigerate until needed.
Bring a large pot of salted water to a boil, and add pasta. Cook, stirring occasionally until tender with a bite, 10 to 12 minutes.
Meanwhile, for sauce, add oil to a skillet and place over medium-high heat. Add seafood and arrange into a single layer. Season with salt and cayenne, and cook and stir for 30 seconds.
Add the garlic; cook, stirring for about 15 seconds. Pour in cream; wait about 1 minute for cream to start to boil. While waiting, add the zest from 1 lemon. Reduce the heat to low, squeeze in juice from half the lemon, or add more to taste. Stir everything together, and turn off heat.
Once pasta is cooked use a strainer to transfer it into the sauce. Turn the heat back on to medium-high, and add tarragon. Stir and toss pasta into sauce with seafood. By the time cream returns to a boil, the seafood will be cooked and pasta is ready to serve.
Turn off heat, and grate in Parmesan cheese. Taste for seasoning and serve immediately in bowls.
