Cook the pasta: Bring a large pot of salted water to a boil. Add the pasta and cook according to package directions until al dente. Drain the pasta, reserving about 1/2 cup of pasta water. Set aside.

Prepare the chicken: Pat the chicken breasts dry with paper towels and season generously with Italian seasoning, salt, and pepper.

Sear the chicken: Heat the olive oil in a large skillet over medium-high heat. Add the chicken breasts and sear for 5-7 minutes per side, or until cooked through and golden brown. An internal temperature of 165°F (74°C) is ideal. Remove the chicken from the skillet and set aside to rest for a few minutes.

Make the sauce: Reduce the heat to medium. Add the minced garlic to the skillet and cook for about 30 seconds, or until fragrant. Be careful not to burn the garlic!

Add the liquids: Pour in the chicken broth and scrape up any browned bits from the bottom of the skillet. Bring the mixture to a simmer and cook for a few minutes to reduce slightly.

Stir in the cream and tomatoes: Stir in the heavy cream and sun-dried tomatoes. Bring the sauce back to a simmer and cook for another 5 minutes, or until the sauce has thickened slightly.

Add the Parmesan: Stir in the grated Parmesan cheese until it's melted and the sauce is smooth and creamy.

Add the Spinach (Optional): If you're using spinach, add it to the sauce and cook until it's wilted, about 2-3 minutes.

Slice the Chicken: Slice the rested chicken breasts into thin slices.

Combine Everything: Add the cooked pasta and sliced chicken to the skillet with the sauce. Toss to coat everything evenly. If the sauce is too thick, add a little of the reserved pasta water until it reaches your desired consistency.

Serve: Serve the Tuscan Chicken Pasta immediately, garnished with extra Parmesan cheese and a sprinkle of fresh parsley, if desired.