Heat olive oil in a large skillet over medium heat. Season the chicken breasts with salt and pepper on both sides.
Add the chicken to the skillet and cook for 6-7 minutes on each side, or until golden brown and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the chopped onion and garlic, sautéing until fragrant and translucent, about 2-3 minutes.
Stir in the chopped sun-dried tomatoes and Italian seasoning. Cook for an additional 2 minutes, allowing the flavors to meld.
Pour in the chicken broth and bring to a simmer. Reduce the heat to low and stir in the heavy cream, mixing until well combined.
Add the fresh spinach to the skillet and cook until wilted, around 2 minutes.
Return the cooked chicken breasts to the skillet, spooning the creamy sauce over the top. Allow to simmer for 5 more minutes to reheat the chicken and blend the flavors.