Pat the chicken dry, then lightly pound it into an even thickness. Season both sides with 1/2 teaspoon of the salt and the pepper.
In a large skillet, heat 1/2 tablespoon of the sun-dried tomato oil over medium high heat. Add 1 tablespoon of the butter, then swirl to melt.
Add the first two pieces of chicken carefully into the skillet. Cook on the first side for 4 minutes, then flip and cook on the second side until golden and the chicken is cooked through, about 3 to 4 minutes more (chicken is considered cooked at 165°F—I prefer to remove it 5 to 10 degrees early, as its temperature will rise as it rests). Transfer to a plate. Add the remaining 1/2 tablespoon sun-dried tomato oil and 1 tablespoon butter. Cook the next two pieces of chicken in the same manner, then remove to a plate.
Reduce the heat to medium, then add the shallot. Cook until the shallot is softened, about 4 minutes. Stir in the garlic, Italian seasoning, and remaining 1/4 teaspoon salt. Let cook just until the garlic is fragrant, about 30 seconds
Add the wine, then scrape to remove any stuck-on browned bits. Simmer until the wine reduces by half, about 2 minutes.
Stir in the spinach a few handfuls at a time, until it wilts.
Stir in the half-and-half and sun-dried tomatoes. Reduce the heat to medium-low and let simmer until slightly thickened, about 3 minutes.
Return the chicken to the skillet, basting it with the sauce to coat. Let warm through for a few minutes. Sprinkle with basil. Enjoy hot.
Notes
TO STORE: Leftover Tuscan chicken can be stored in an airtight container in the refrigerator for up to 3 days.
TO REHEAT: I recommend warming the sauce in a small saucepan over medium-low heat and warming the chicken breasts in the microwave for best results. Then, pour the sauce over the chicken and serve.
TO FREEZE: Freeze Tuscanchicken in an airtight, freezer-safe storage container for up to 3 months. Thaw overnight in the refrigerator before reheating according to the instructions above.