1. Season chicken
Prep the chicken. Season both sides of each chicken breast in Italian seasoning, salt, and pepper.
2. Sear chicken
Sear the chicken. 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.
3. Cook onions
Cook the onions. In the same skillet, add another tablespoon of oil and the onion. Saute for 2 to 3 minutes, until the onion has softened.
4. Cook tomatoes and garlic
Add the sun-dried tomatoes and garlic and saute another minute, until fragrant.
5. Add spinach
Add the spinach, and saute another minute, until just starting to wilt.
6. Add cream and cheese
Add the heavy cream and parmesan cheese, stir together, and bring to a simmer.
7. Simmer
Let it simmer. Place the chicken back in the skillet and cook until heated through, about 5 minutes.