Season chicken with salt and pepper. Heat olive oil in a skillet over medium heat. Cook chicken 6-7 minutes per side until golden and cooked through. Set aside.

Sauté onion in the same skillet for 3-4 minutes until softened. Add garlic and cook 1-2 minutes until fragrant.

Add mushrooms and cook 5-6 minutes until browned and tender. Stir in spinach and cook 2-3 minutes until wilted.

Pour in chicken broth and heavy cream. Stir in Parmesan, Italian seasoning, and red pepper flakes. Simmer 5-7 minutes until sauce thickens slightly.

Return chicken to the skillet, spooning sauce over the top. Simmer for 5 minutes to meld flavors.

Serve chicken with sauce, spinach, and mushrooms over pasta, rice, or mashed potatoes.