Prepare the chicken:
a. Preheat the oven to 400°F (200°C).
b. In a small bowl, combine the lemon pepper seasoning, garlic powder, onion powder, thyme, salt, and pepper.
c. Rub the chicken breasts with olive oil and sprinkle the seasoning mix over both sides of each chicken breast.
d. Squeeze the juice of one lemon over the chicken and sprinkle with lemon zest. Set the chicken aside to marinate while you prepare the rice and vegetables.

Cook the rice:
a. In a medium saucepan, bring the chicken broth (or water) to a boil.
b. Add the rice, lower the heat to a simmer, cover, and cook for 15-18 minutes (or according to the rice package instructions).
c. Once the rice is done, remove from heat and let it sit, covered, for 5 minutes. Fluff with a fork.

Cook the chicken:
a. Heat 1 tablespoon of olive oil in a large oven-safe skillet over medium-high heat.
b. Add the seasoned chicken breasts to the skillet and sear for 3-4 minutes per side until golden brown.
c. Transfer the skillet to the oven and bake the chicken for 15-20 minutes, or until the internal temperature reaches 165°F (75°C). Remove from the oven and let it rest.

Cook the zucchini and squash:
a. While the chicken is cooking, heat another tablespoon of olive oil in a large skillet over medium heat.
b. Add the diced onions and garlic and sauté for 2-3 minutes until softened.
c. Add the sliced zucchini and squash to the skillet and cook for 5-6 minutes, stirring occasionally, until tender and lightly browned. Season with salt and pepper to taste.

Assemble the dish:
a. Serve the cooked rice on a plate or in a bowl. Top with the sautéed zucchini and squash.
b. Slice the baked lemon pepper chicken and arrange it on top of the rice and vegetables. Garnish with fresh parsley if desired.

Serve:
a. Enjoy your Lemon Pepper Chicken and Rice with Zucchini and Squash!