Season both sides of each chicken breast with Italian seasoning, salt, and pepper.

Heat 2 tablespoons of the oil in a large skillet over medium heat. Add the chicken and sear for 3 to 4 minutes on each side, until golden. Remove the chicken from the pan to a plate and set aside.

In the same skillet, add another tablespoon of oil and the onion. Sauté for 2 to 3 minutes, until the onion has softened.

Add the sun-dried tomatoes and garlic and sauté another minute, until fragrant.

Add the spinach and sauté another minute, until just starting to wilt.

Add the heavy cream and parmesan cheese, stir together, and bring to a simmer.

Place the chicken back in the skillet and cook until heated through, about 5 minutes.