In a bowl, mix the chicken with olive oil, Italian seasoning, salt, garlic powder, oregano, black pepper, and red pepper flakes to marinate evenly.
Heat a skillet or pan over medium-high heat with oil.
Add the marinated chicken to the pan and cook until golden brown on each side, about 3 minutes per side. Reduce heat to low and cook until the chicken reaches 165°F. Remove from the pan.
**Make the Tuscan Sauce:**
In the same pan over medium heat, add lemon juice and butter. Scrape the bottom of the pan and add garlic and tomatoes. If desired, add onions too. Sauté for a minute or two.
Pour in heavy cream and chicken broth. Whisk and simmer for 2 to 3 minutes.
Add cream cheese and parmesan, whisk until the sauce thickens. Season with salt and black pepper.