In a large pot, bring salted water to a rolling boil over high heat. Add pasta and cook according to package instructions, about 10-12 minutes, until al dente. Reserve about ½ cup of the cooking water before draining.

Season chicken breasts with salt, pepper, and Italian seasoning. Lightly coat in flour. Set aside.

In a skillet over medium-high heat, add olive oil. Once hot, place the chicken in the skillet, cooking for about 5-7 minutes until golden brown. Flip and cook until no longer pink. Remove and set aside.

In the same skillet, reduce heat to medium and add butter. Once melted, add chopped onion and sauté for 3-4 minutes until soft. Add minced garlic and cook for an additional minute.

Deglaze the skillet with chicken broth, scraping up any bits. Bring to a gentle boil, stir in pesto, and reduce to a simmer.

Add half-and-half and garlic powder, stirring continuously for 2-3 minutes until the sauce thickens slightly.

Return cooked chicken to the skillet, let simmer for 3-4 minutes. Prepare to add pasta.

Add drained pasta to the skillet, tossing gently to coat. Adjust sauce consistency with reserved pasta water as needed. Stir in Parmesan until melted.

Serve warm, garnished with chopped basil if desired.