Begin by patting the chicken breasts dry with a paper towel and seasoning them generously with salt and pepper on both sides.
In a large, oven-safe skillet or Dutch oven, heat the olive oil over medium-high heat. Once the oil is shimmering, add the seasoned chicken breasts and sear them for 3-4 minutes per side, or until they develop a golden-brown crust.
In the same pan, reduce the heat to medium and add the minced garlic. Sauté the garlic for 1-2 minutes, stirring constantly, until fragrant and slightly softened.
Pour in the heavy cream and grated Parmesan cheese. Whisk the mixture together until the cheese has melted and the sauce is smooth and creamy. Add the diced tomatoes, chopped spinach, dried basil, and dried oregano. Stir to combine, and let the sauce simmer for 2-3 minutes to allow the flavors to meld.
Return the seared chicken breasts to the pan, nestling them into the creamy Tuscan-style sauce. Cover the pan with a lid or aluminum foil and transfer it to a preheated 375°F oven. Bake the chicken for 20-25 minutes, or until it reaches an internal temperature of 165°F.
Once the chicken is cooked through, remove the pan from the oven and let it rest for 5 minutes. Serve the Creamy Tuscan Garlic Chicken immediately, spooning the flavorful sauce over the top of the chicken.
