Prepare the Chicken: Pat the chicken breasts dry with paper towels. Season both sides with salt, black pepper, garlic powder, and Italian seasoning.
Sear the Chicken: Heat olive oil and butter in a large skillet over medium-high heat. Add the chicken and cook for 5–6 minutes per side until golden brown and fully cooked through (internal temperature should reach 165°F / 74°C). Remove the chicken from the skillet and set aside on a plate. Make the Creamy Spinach Sauce: In the same skillet, melt 2 tablespoons of butter. Add minced garlic and sauté for 30 seconds until fragrant. Pour in chicken broth and heavy cream, stirring to combine. Bring the mixture to a gentle simmer.
Add Spinach and Cheese: Stir in the Parmesan cheese until melted and smooth. Add chopped spinach and cook for 1–2 minutes until wilted. Season with salt, pepper, and red pepper flakes (if using). Stir in a splash of lemon juice for a hint of brightness.
Combine and Serve: Return the chicken breasts to the skillet, spooning sauce over the top. Simmer for another 2–3 minutes to allow the flavors to meld.