Lightly coat the inside of your slow cooker with non-stick cooking spray or drizzle some olive oil.
In a skillet over medium heat, add olive oil. Sauté the chopped onion until it becomes translucent, about 4–5 minutes. Then add minced garlic and cook for an additional minute.
In the slow cooker, add the sautéed onion and garlic mixture first. Next, layer the rice evenly at the bottom.
In a bowl, mix together chicken broth, lemon juice, lemon zest, Italian herbs, salt, and pepper. Pour this mixture over the rice in the slow cooker.
Place the chicken breasts on top of the rice mixture.
Sprinkle frozen peas and carrots on top of the chicken.
Cover your slow cooker and set it on low for 4 to 6 hours or on high for 2 to 3 hours.
Verify that your chicken reaches an internal temperature of at least 165°F (74°C) and check that the rice has absorbed all liquid.
Before serving, gently fluff the rice with a fork to separate the grains.
Sprinkle chopped fresh parsley over the top for an added touch of color and flavor before serving.