Season chicken with salt, pepper and smoked paprika. Heat 1 tbsp olive oil and 1 tbsp butter in a large skillet over medium-high heat. Sear chicken 4–5 minutes per side until golden and cooked through. Remove and tent with foil.
Reduce heat to medium, add remaining oil and butter. Sauté mushrooms until browned, then add onion/shallot and cook until translucent. Stir in garlic and cook 30 seconds.
Pour in wine or 1/2 cup broth to deglaze, scraping up browned bits. Reduce slightly, then stir in cream, chicken broth, Parmesan and Dijon. Simmer until slightly thickened.
Stir in spinach until wilted. Return chicken to the pan, spoon sauce over, and warm 2 minutes. Garnish with parsley and extra Parmesan before serving.
Notes
Pound chicken to even thickness for quicker, even cooking.
Use half-and-half for a lighter sauce or coconut cream for dairy-free.
Add lemon juice or sun-dried tomatoes to brighten the sauce.