Set a large pot of water on high heat to boil, season it with salt and let it come to a boil as you cook the rest of the meal. Once it's boiling, add in the pasta and let it cook while you finish the sauce.
1½ tablespoon kosher salt, 6 cups water
Season the chicken thighs on both sides with salt and pepper. Heat vegetable oil in a large skillet over medium-high heat and sear the chicken until golden brown on both sides, about 3-4 minutes. Remove the thighs from the pan and set aside on a plate.
1 ½ lbs chicken thighs, 2 teaspoon kosher salt, 1 teaspoon freshly ground black pepper, 2 tablespoon vegetable oil
Turn the heat to medium, then add the shallots, red pepper flakes, and thyme with a nice pinch of salt. Cook 2-3 minutes until the shallots are softened and turning a little golden. Add in the garlic and cook for another minute, until it's nice and fragrant.
1 shallot, ½ teaspoon dried thyme, ¼ teaspoon red pepper flakes, 5 cloves garlic
Pour in the sherry and scrape up all those browned bits from the bottom of the pan with a wooden spoon. Let it simmer for about a minute to cook out the alcohol.
½ cup dry sherry
Add the chicken broth and return the chicken to the pan. Simmer for 6-7 minutes, until the chicken is cooked through (internal temperature 165ºF) and the broth has reduced slightly.
1 ½ cups chicken broth
Remove the chicken thighs and chop them into bite-sized pieces on a cutting board.
Stir the heavy cream into the pan. If the sauce looks thin or broken, mix the softened butter and flour together until they're combined into one buttery lump to make a beurre manié, then whisk small pieces into the sauce until it smooths out and thickens.
2 tablespoon unsalted butter, 2 tablespoon all-purpose flour, 1 cup heavy cream
Take the pan off the heat and stir in the Parmesan until it melts and turns silky.
1 cup freshly grated Parmesan cheese
Add the chopped chicken back to the pan and stir to coat.
Add the cooked pasta and toss everything together, splashing in a bit of reserved pasta water if needed to loosen the sauce. Taste and adjust seasoning with salt and pepper. Garnish with parsley and serve hot.
12 oz short-cut pasta , kosher salt and freshly ground black pepper, chopped parsley