Prep the chicken. Place a hand on top of each breast and carefully slice horizontally to create thin cutlets. Pat dry.
Season both sides with salt and pepper.
Dredge lightly. Mix the flour with the garlic powder. Dredge each cutlet, shaking off excess. You want a whisper-thin coating, not clumps.
Brown in batches. Heat 1 tablespoon olive oil in a large skillet over medium-high.
Add half the chicken and cook 2–3 minutes per side until golden and just cooked through. Transfer to a plate. Repeat with the remaining oil and chicken.
Build flavor. Reduce heat to medium.
Add the butter to the pan. When melted, add the sliced garlic. Cook 30–45 seconds until fragrant, stirring so it doesn’t brown too much.
Deglaze. Pour in the chicken broth.
Scrape up the browned bits—this is where the flavor lives. Let it simmer 2 minutes to reduce slightly.
Add lemon and capers. Stir in the lemon juice, capers, and red pepper flakes if using. Simmer 1–2 minutes more, until the sauce looks glossy and slightly thickened.
Return the chicken. Nestle the cutlets and any juices back into the pan.
Spoon sauce over the top and simmer 1–2 minutes to warm through. Taste and adjust salt and pepper.
Finish and serve. Sprinkle with parsley, add lemon slices if you like, and serve hot. Great over cauliflower rice, farro, or whole-wheat angel hair with a side of sautéed greens.