Prep the Chicken: Season the chicken breasts with salt and pepper on both sides.
Cook the Chicken: Heat olive oil in a large skillet over medium-high heat. Add chicken breasts to the pan and cook for 3-4 minutes per side until golden brown and cooked through. Remove the chicken from the skillet and set aside.
Cook the Mushrooms: In the same skillet, add sliced mushrooms and cook for 3-4 minutes until soft and golden.
Make the Sauce: Add chicken broth to the pan, scraping up any browned bits from the bottom. Stir in lemon juice, capers, and chicken broth. Let the sauce simmer for 3 minutes to reduce slightly.
Finish the Dish: Add the chicken back to the skillet, spooning the sauce and mushrooms over the chicken. Let it simmer for 2-3 minutes to reheat the chicken and allow the flavors to meld together.
Serve: Remove from heat, add butter to the sauce to thicken it, and garnish with fresh parsley. Serve hot with your favorite side dish.