Pound the chicken to an even thickness and season both sides with salt, pepper, garlic powder, and 1 tsp dried parsley.
Heat a large skillet over medium-high heat and add 1 tsp olive oil and 2 tbsp butter.
Sear the chicken 2 minutes per side, until browned but not fully cooked through, then transfer to a plate.
Add the uncooked rice to the skillet and stir briefly to coat and loosen browned bits from the pan.
Pour in 2 1/4 cups chicken stock, add lemon zest, 3 tbsp lemon juice, and 1 tsp dried parsley (or fresh), and bring to a gentle boil.
Reduce heat to low, nestle the seared chicken on top of the rice, cover, and simmer 20–22 minutes until rice is tender and liquid is absorbed and chicken is cooked through.
Fluff the rice with a fork, garnish with lemon slices and extra parsley if desired, and serve immediately.