Pound 4 chicken breasts to an even thickness, about ½ inch thick. Season with salt and pepper.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the chicken to the skillet and cook for about 5-6 minutes per side, until cooked through and golden brown. Remove the chicken to a plate and set aside.
To the same skillet, add 1 tablespoon butter, 1 finely minced shallot, 2 teaspoons minced garlic, and 2 cups sliced mushrooms. Cook for 3-4 minutes, until the mushrooms begin to soften.
Add ½ cup brandy or cognac to the skillet and cook for 1 minute until the alcohol is reduced. Use a spatula to scrape any browned bits from the bottom of the skillet.
Stir in 1 cup chicken broth and bring to a boil. Cook until thickened, about 2 minutes.
Reduce the heat and whisk in ¾ cups heavy cream, 2 tablespoons lemon juice, 1 tablespoon Dijon mustard, and 2 teaspoons Worcestershire sauce. Let the sauce simmer for 2-3 minutes, until slightly thickened.
Add the chicken back to the skillet, spoon the sauce over the chicken, and heat through for a few minutes. Season with additional salt and pepper if needed, garnish with fresh parsley, and serve.
Notes
Storage Tips
Fridge: Store in an airtight container for up to 4 days. Reheat in the microwave or on the stovetop until warmed through.
Freezer: Not recommended.
Make Ahead: Cook the chicken and sauce ahead of time and store separately. Reheat gently on the stovetop, adding a splash of broth if needed.