Season chicken breasts with salt and pepper to taste.
Heat olive oil in a large skillet over medium-high heat. Add chicken and cook until browned and almost cooked through. Remove the chicken from the pan and set it aside.
In the same pan, reduce heat to medium and cook butter, onion, and garlic until the onion is tender.
Add chicken broth and simmer for 3-5 minutes, or until reduced by half. Stir in cream cheese until melted.
Add heavy cream and simmer for 3-4 minutes, or until it slightly thickens. Add the cooked chicken and fresh spinach. Simmer until the chicken is cooked through and the spinach is wilted, about 3 minutes more.
Stir in Parmesan cheese and chili flakes.
Serve over cauliflower rice or zucchini noodles.