Bring a large pot of well-salted water to a boil. Cook penne according to package directions until al dente, 10 to 12 minutes. Before draining, reserve 1 cup of pasta cooking water. Drain the pasta and set aside.

While pasta cooks, pat chicken pieces dry with paper towels. Toss with Italian seasoning, paprika, salt, and black pepper until evenly coated.

Heat olive oil in a large, deep skillet over medium-high heat until shimmering. Add seasoned chicken in a single layer and cook undisturbed for 3 to 4 minutes until golden brown. Flip and cook another 3 to 4 minutes until cooked through and golden on all sides. Transfer chicken to a plate and set aside.

Reduce heat to medium. Add minced garlic to the same skillet and sauté for about 1 minute, stirring constantly, until fragrant but not browned.

Pour in chicken stock and use a wooden spoon to scrape up all the browned bits from the bottom of the pan. Let simmer for 1 to 2 minutes to reduce slightly, then stir in heavy cream, chopped sun-dried tomatoes, and red pepper flakes if using.

Sprinkle in grated Parmesan cheese, stirring constantly as it melts. Let the sauce simmer gently for 3 to 5 minutes until thickened and velvety, coating the back of a spoon.

Return the seared chicken and any accumulated juices to the skillet. Add the drained pasta and chopped fresh basil. Toss everything together using tongs until every piece is coated in sauce. Add reserved pasta water a few tablespoons at a time if the sauce seems too thick.

Taste and adjust seasoning with additional salt and pepper if needed. Garnish with extra fresh basil and grated Parmesan. Serve immediately while hot.