Slice each chicken breast in half lengthwise to make four thinner chicken breast cutlets. Season both sides with salt and pepper.
In a shallow bowl, combine ½ cup of flour, salt, black pepper, and garlic powder, mixing until combined. Dredge each chicken cutlet in the flour so that both sides are completely coated in flour. Set aside.
Heat the olive oil in a large skillet set over medium heat. Add the dredged chicken breasts to the skillet and cook for approximately 3 minutes on each side or until golden brown and the chicken is cooked through. Remove the chicken to a clean plate and set them aside.
In the same skillet over medium heat, melt the butter. Add the minced garlic and cook, stirring continuously, for about 30 seconds or until fragrant.
Whisk the remaining 2 tablespoons of flour into the butter and garlic. Sauté the flour and butter mixture for about a minute, stirring continuously to prevent the flour from burning (it will resemble a paste).
Whisk the wine and chicken broth in the garlic and flour mixture. At the same time, scrape up any brown bits that may be stuck to the bottom of the pan and bring to a simmer over medium heat. Simmer for about 5 minutes or until the broth begins to change color and reduce.
Add the sliced mushrooms and cook for approximately 8-10 minutes, or until the mixture turns a deep brown color.
Finally, stir in the heavy cream and simmer over medium-low heat for 5 minutes. Do not boil. Return the chicken back to the pan.
Remove from heat and season with salt and pepper, to taste. Stir in the chopped parsley.