Bring a large pot of salted water to a boil. Cook the pasta according to package directions. Reserve 1 cup of the starchy pasta water, then drain the pasta and set aside.
8 ounces uncooked pasta
Meanwhile, season the chicken pieces with salt and pepper. Heat oil in a large skillet over medium-high heat. Add chicken pieces, spacing them apart and working in batches if needed. Cook for 3-4 minutes without moving until nicely seared on the bottom. Turn the pieces over and continue to cook the chicken, stirring occasionally, until cooked through or they reach 165 degrees F when tested with a digital meat thermometer. Transfer to a plate and cover with foil to keep warm.
1 ½ pounds boneless skinless chicken breasts, 1 teaspoon coarse kosher salt, ½ teaspoon freshly ground black pepper, 1 Tablespoon olive oil
To the same pan, add the butter and let it melt. Add the onion, sauteeing and scraping up the browned bits (called "fond") from the bottom of the pan. Cook for 3-5 minutes until softened. Add garlic and cook for another 30 seconds.
2 Tablespoons salted butter, ½ large onion
Sprinkle the flour over the cooked onions and stir until absorbed and the raw taste of the flour is removed, about 30 to 60 seconds.
3-4 cloves garlic, 2 teaspoons all-purpose flour
Whisk in the chicken broth, scraping any browned bits off the bottom of the pan and letting it come to a simmer for 1 minute.
1 cup chicken broth
Stir in the heavy cream, sun-dried tomatoes, Italian seasoning, smoked paprika, and red pepper flakes. Return the chicken to the pan. Cook for 2-3 minutes or until the sauce has thickened slightly.
1 cup heavy cream, ½ cup sundried tomatoes, 1 teaspoon Italian seasoning, ¼ teaspoon crushed red pepper flakes
Stir in the parmesan cheese and basil, then remove the skillet from the heat and add the cooked pasta. Toss the pasta in the sauce until evenly coated, adding as much of the reserved pasta water as needed to get a consistency you like. I usually use around 1/2 cup of the pasta water. Taste and adjust the seasoning as needed, Sprinkle with additional Parmesan cheese or fresh basil just before serving.
½ cup freshly grated Parmesan cheese, 1 handful fresh basil leaves