Start by patting the chicken breasts dry with paper towels. Season both sides with salt and black pepper.
In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Once hot, add the chicken breasts and sear for about 5-7 minutes on each side, or until golden brown and cooked through. Use a meat thermometer to ensure they reach an internal temperature of 165°F. Remove the chicken and set aside.
In the same skillet, add the remaining tablespoon of olive oil. Add the diced onion and sauté until translucent, about 3-4 minutes. Stir in the minced garlic and cook for an additional minute until fragrant.
Add the can of tomato sauce, heavy whipping cream, and grated parmesan cheese to the skillet. Stir to combine and bring to a gentle simmer. Add the Italian seasoning, and season with salt and pepper to taste.
Return the seared chicken breasts to the skillet, spooning the sauce over them. Allow everything to simmer together for about 5 minutes, ensuring the chicken is heated through and coated in the creamy sauce.
Just before serving, sprinkle the shredded parmesan cheese over the top of the chicken. Optionally, garnish with additional Italian seasoning. Serve warm over pasta, rice, or with crusty bread.