Warm the olive oil in a large saucepan over medium heat.
Season the chicken generously with salt and pepper, then cook it for about 3 to 5 minutes on each side until fully cooked and no longer pink inside.
Take the chicken out and set it aside on a plate.
Add butter to the same pan along with the diced onions, minced garlic, and crushed red pepper; cook everything together for 1 to 2 minutes until fragrant.
Pour in the heavy cream and chicken broth, then add the sun-dried tomatoes and softened cream cheese. Stir and let it simmer on medium heat until the sauce becomes smooth and creamy.
Mix in the grated Parmesan and the fresh spinach leaves, cooking just long enough for the spinach to wilt and the sauce to thicken slightly.
Season the sauce with salt and pepper to your liking.
Place the cooked chicken back into the pan, coating it with the sauce and warming it through.
Serve the dish garnished with fresh chopped basil if you like, either on its own, over pasta, or with cauliflower rice for a low-carb option.