Prep the chicken. Pat the chicken breasts dry. Pound to even thickness so they cook evenly.
In a shallow bowl, mix flour, salt, pepper, and Italian seasoning. Dredge chicken lightly, shaking off excess.
Sear the chicken. Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat. Add chicken and cook 4–6 minutes per side, until golden and just cooked through.
Transfer to a plate; tent with foil.
Sauté aromatics. Reduce heat to medium. Add remaining 1 tablespoon butter. Stir in garlic and sun-dried tomatoes.
Cook 30–60 seconds until fragrant. Don’t let the garlic burn.
Deglaze and build the sauce. Pour in chicken broth, scraping up browned bits. Simmer 2 minutes to reduce slightly.
Stir in cream, Parmesan, Dijon (if using), and red pepper flakes. Whisk until smooth.
Simmer to thicken. Let the sauce bubble gently for 3–4 minutes, stirring. It should coat the back of a spoon.
If it’s too thick, add a splash of broth. Too thin? Simmer another minute.
Add greens and return chicken. Stir in spinach until just wilted.
Nestle chicken back into the pan with any juices. Spoon sauce over the chicken and warm for 2 minutes.
Finish and serve. Taste and adjust seasoning with salt and pepper. For brightness, squeeze a little lemon over the top.
Garnish with fresh basil. Serve hot with pasta, rice, or crusty bread.