Heat the skillet: Set a large skillet with a lid over medium-high heat and add the olive oil.

Season the chicken: Pat the chicken thighs dry and season both sides with 3/4 teaspoon of the salt and all of the black pepper.

Brown the chicken: Put the chicken in the hot skillet and cook for 4 to 5 minutes per side, until both sides are deep golden brown.

Set the chicken aside: Transfer the chicken to a plate and keep the skillet on the stove.

Cook the garlic: Lower the heat to medium, add the garlic to the skillet, and stir for 30 seconds.

Toast the rice: Add the rice to the skillet and stir for 1 minute, until the grains look glossy.

Add the water and lemon: Pour the water into the skillet, add the lemon zest, the remaining 3/4 teaspoon of salt, and half of the lemon juice, and scrape the bottom of the pan to loosen the browned bits.

Return the chicken: Put the chicken and any juices from the plate back into the skillet, press the chicken lightly into the rice, and let the liquid come to a gentle simmer.

Cover and cook: Cover the skillet, lower the heat to low, and cook for 18 to 20 minutes, until the rice is tender and the chicken is cooked through.

Wilt the spinach: Turn off the heat, scatter the spinach over the rice, and cover the skillet for 2 minutes.

Finish and serve: Uncover the skillet, stir the spinach into the rice, squeeze the remaining lemon juice over the top, and serve.