Begin by seasoning each chicken breast evenly with the Italian seasoning, kosher salt, and black pepper to infuse the meat with fragrant herbs and balanced seasoning.
Heat 2 tablespoons of olive oil over medium heat in a large skillet. Once hot, add the chicken breasts and sear each side for approximately 3 to 4 minutes, until a golden-brown crust forms. Remove the chicken from the skillet and place it on a plate to rest.
In the same skillet, add the remaining tablespoon of olive oil. Toss in the chopped onions and sauté them for 2 to 3 minutes, stirring occasionally, until they soften and turn translucent.
Add the minced garlic and sliced sun-dried tomatoes to the pan and cook for another minute, allowing the garlic to become fragrant and the tomatoes to slightly rehydrate.
Stir in the baby spinach and cook for about one minute, just until it begins to wilt and blend with the other ingredients.
Pour in the heavy cream and sprinkle the Parmesan cheese. Stir the mixture thoroughly and bring it to a gentle simmer, letting the sauce thicken and the cheese melt completely.
Return the chicken breasts to the skillet, nestling them into the creamy sauce. Let everything cook together for about 5 minutes, ensuring the chicken is heated through and infused with the sauce’s rich flavors.