Season the chicken all over with salt, pepper, and garlic powder.
Heat the oil in a large skillet over medium-high heat. Sear the chicken 5-6 minutes per side until golden and cooked through (165°F inside). Remove to a plate.
Lower heat to medium. Melt 2 tbsp butter, add the garlic, and stir 30 seconds.
Add the green beans and chicken broth. Cover and cook 4-5 minutes until crisp-tender.
Uncover, add the remaining 2 tbsp butter and lemon juice. Toss until the butter melts into a glossy sauce.
Slice the chicken, arrange over the green beans, and spoon the sauce over everything. Shower with parsley.