Step 1: Place chicken breasts between two pieces of plastic wrap and pound to 1/4-inch thickness using a meat mallet or rolling pin.
Step 2: In a shallow dish, combine flour, salt, and pepper. Dredge chicken breasts in the flour mixture, shaking off excess.
Step 3: Heat olive oil in a large skillet over medium-high heat. Add chicken and cook for 3-4 minutes per side until golden brown and cooked through. Transfer to a plate.
Step 4: Reduce heat to medium and add butter to the skillet. Once melted, add chicken broth, lemon juice, and capers. Bring to a simmer, scraping up any browned bits from the bottom of the pan.
Step 5: Return chicken to the skillet and simmer for 2-3 minutes to heat through and allow flavors to combine.
Step 6: Sprinkle with chopped parsley and garnish with lemon slices if desired. Serve immediately.