01 - Season both sides of the chicken breasts evenly with salt and black pepper.
02 - Heat olive oil in a large skillet over medium-high heat. Add chicken and sear for 5-6 minutes per side until golden brown and cooked through. Transfer chicken to a plate and reserve.
03 - In the same skillet, add chopped onion and sauté for 2-3 minutes until translucent. Add minced garlic and cook for 1 minute until fragrant.
04 - Stir in sliced sundried tomatoes and cook for 1 minute to release their flavors.
05 - Pour in chicken broth and scrape up browned bits from the bottom of the skillet. Reduce heat to medium.
06 - Add heavy cream, Parmesan cheese, Italian seasoning, and crushed red pepper flakes. Stir continuously until sauce is smooth and begins to thicken, about 2-3 minutes.
07 - Add fresh spinach and cook for 2 minutes until just wilted.
08 - Return chicken breasts to the skillet, nestling them into the sauce. Simmer for 3-4 minutes until chicken is heated through and flavors have melded together.
09 - Sprinkle with chopped fresh parsley and serve immediately while hot.