Season the chicken cutlets on both sides with salt and pepper and pat dry so they brown well.
Heat the olive oil and butter in a large skillet over medium-high heat, then sear the chicken for 4–5 minutes per side until golden and cooked through; transfer to a plate and cover.
Reduce heat to medium, add the diced onion, and cook until softened, scraping up browned bits from the pan.
Stir in the garlic, oregano, thyme, and smoked paprika and cook for about 1 minute until fragrant.
Add the sun-dried tomatoes and olives to the skillet and cook for another minute to warm through.
Pour in the chicken broth and simmer for 3–4 minutes, stirring and reducing slightly.
Stir in the heavy cream and cream cheese, whisking until the sauce is smooth and lightly thickened.
Fold in the spinach and cook until just wilted, then return the chicken and any juices to the skillet, nestling it into the sauce.
Simmer for 3–5 minutes until the chicken is heated through, then finish with lemon juice, feta, and parsley before serving.