Place a chicken breast flat on a cutting board. Hold your knife parallel to the cutting board and carefully slice through the middle of the breast horizontally to create two thinner cutlets of even thickness. Repeat with the second breast. Pat the cutlets dry with a paper towel; this helps them sear better and get a crispier crust. In a shallow dish, whisk together the flour, salt, pepper, and garlic powder. Dredge each chicken cutlet in the flour mixture, ensuring it’s lightly coated on all sides. Gently shake off any excess flour.
Heat a large skillet or frying pan over medium-high heat. Add the olive oil and 1 tablespoon of the butter. Once the butter has melted and the pan is shimmering, carefully place the floured chicken cutlets in the skillet in a single layer. Be careful not to overcrowd the pan; cook in two batches if necessary. Cook for 4-5 minutes per side, until the chicken is golden brown and cooked through. The internal temperature should reach 165°F (74°C). Once cooked, remove the chicken from the pan and set it aside on a plate.
Reduce the heat to medium. In the same skillet, pour in the chicken broth to deglaze the pan, using a wooden spoon or spatula to scrape up any browned bits (the “fond”) from the bottom—this is where a ton of flavor is! Stir in the fresh lemon juice and lemon zest. Bring the sauce to a gentle simmer and let it bubble for 2-3 minutes to allow the flavors to meld and the sauce to reduce slightly.
Stir the remaining 2 tablespoons of butter into the sauce until it has melted completely. This will make the sauce glossy and rich. Return the seared chicken to the skillet, nestling it into the sauce. Let it simmer gently for another 1-2 minutes, spooning the sauce over the chicken to ensure it’s well-coated and reheated.
Take the skillet off the heat. Taste the sauce and adjust the seasoning with more salt or pepper if needed. Garnish generously with fresh chopped parsley if you are using it. Serve immediately and enjoy!