Pat the chicken dry, season with salt, pepper, and Italian seasoning, and let rest for 5 minutes.

Heat olive oil and butter in a skillet over medium heat. Sauté seasoned chicken for 5-7 minutes until golden brown and cooked through.

In the same skillet, add olive oil and butter, then sauté diced onion for 5 minutes until translucent. Add minced garlic and cook for 1 minute.

Add chopped sun-dried tomatoes, red pepper flakes, and Italian seasoning to the skillet. Cook for 2 minutes.

Pour in chicken broth and let simmer for 3 minutes. Stir in heavy cream and simmer for another 5 minutes until thickened.

Reduce heat to low and stir in grated Parmesan until melted. Adjust salt and pepper as needed.

Cook fettuccine according to package instructions until al dente. Reserve ½ cup pasta water, then drain.

Toss drained fettuccine with the creamy sauce, adding sliced chicken and reserved pasta water for desired consistency.

Mix in freshly chopped basil just before serving, and garnish with additional Parmesan and red pepper flakes if desired.